diff --git a/TODO.txt b/TODO.txt
new file mode 100644
index 0000000..e8a214f
--- /dev/null
+++ b/TODO.txt
@@ -0,0 +1,16 @@
+Modes:
+    Tetris
+    Matrix
+    Ludo
+    Pacman
+    Snake
+    Strobe
+
+Improvements:
+    NewYear => change due date (birthday etc)
+
+Hardware:
+    Gamepads
+    Heatsink
+    Extend Matrix (double?)
+    Microphone
diff --git a/platformio.ini b/platformio.ini
index 36c09d6..c63c4b4 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -20,3 +20,4 @@ upload_protocol = espota
 ;upload_speed = 921600
 monitor_port = /dev/ttyUSB0
 monitor_speed = 115200
+monitor_filters = esp32_exception_decoder
diff --git a/src/BASICS.h b/src/BASICS.h
index 79b74f3..52a7a10 100644
--- a/src/BASICS.h
+++ b/src/BASICS.h
@@ -9,8 +9,12 @@
 #define ____ 0
 #define FULL 255
 
+#define countof(x)      (sizeof(x) / sizeof(x[0]))
+
 typedef int64_t microseconds_t;
 
+typedef unsigned long millis_t;
+
 double doStep(double valueCurrent, double valueMin, double valueMax, microseconds_t millisecondsTotal, microseconds_t microsecondsDelta);
 
 bool randomBool(int uncertainty);
diff --git a/src/config.cpp b/src/config.cpp
index fb388a4..b08e2de 100644
--- a/src/config.cpp
+++ b/src/config.cpp
@@ -16,7 +16,7 @@ bool dirty = false;
 
 bool notify = false;
 
-unsigned long lastDirtyMillis = 0;
+millis_t lastDirtyMillis = 0;
 
 void config_setup() {
   if (!config_load()) {
diff --git a/src/display/Display.h b/src/display/Display.h
index ee223b0..17b0b7e 100644
--- a/src/display/Display.h
+++ b/src/display/Display.h
@@ -29,7 +29,7 @@ private:
 
     Adafruit_NeoPixel leds;
 
-    unsigned long fpsLastMillis = 0;
+    millis_t fpsLastMillis = 0;
 
     int fps = 0;
 
diff --git a/src/mode.cpp b/src/mode.cpp
index 5fb99fe..cb60bab 100644
--- a/src/mode.cpp
+++ b/src/mode.cpp
@@ -8,12 +8,13 @@
 #include "mode/NewYear/NewYear.h"
 #include "mode/Starfield/Starfield.h"
 #include "display.h"
+#include "mode/Matrix/Matrix.h"
 
 ModeId currentModeId = NONE;
 
 microseconds_t lastMicros = 0;
 
-ModeBase *mode = nullptr;
+Mode *mode = nullptr;
 
 void unloadOldMode();
 
@@ -22,6 +23,8 @@ void loadNewMode();
 void mode_step();
 
 void mode_loop() {
+  Serial.print("\n");
+
   if (currentModeId != config.mode) {
     unloadOldMode();
     loadNewMode();
@@ -49,6 +52,7 @@ void setSpeed(double speed) {
 
 void unloadOldMode() {
   if (mode != nullptr) {
+    Serial.print("[MODE] unload\n");
     delete mode;
     mode = nullptr;
   }
@@ -58,36 +62,40 @@ void unloadOldMode() {
 void loadNewMode() {
   currentModeId = config.mode;
   lastMicros = 0;
+  Serial.printf("[MODE] loading %d\n", currentModeId);
   switch (currentModeId) {
     case BORDER:
-      mode = new Border(&display);
+      mode = new Border(display);
       break;
     case CLOCK:
-      mode = new Clock(&display);
+      mode = new Clock(display);
       break;
     case GAME_OF_LIFE_BLACK_WHITE:
-      mode = new GameOfLife(&display, BLACK_WHITE);
+      mode = new GameOfLife(display, BLACK_WHITE);
       break;
     case GAME_OF_LIFE_GRAYSCALE:
-      mode = new GameOfLife(&display, GRAYSCALE);
+      mode = new GameOfLife(display, GRAYSCALE);
       break;
     case GAME_OF_LIFE_COLOR_FADE:
-      mode = new GameOfLife(&display, COLOR_FADE);
+      mode = new GameOfLife(display, COLOR_FADE);
       break;
     case GAME_OF_LIFE_RANDOM_COLOR:
-      mode = new GameOfLife(&display, RANDOM_COLOR);
+      mode = new GameOfLife(display, RANDOM_COLOR);
       break;
     case PONG:
-      mode = new Pong(&display);
+      mode = new Pong(display);
       break;
     case SPACE_INVADERS:
-      mode = new SpaceInvaders(&display);
+      mode = new SpaceInvaders(display);
       break;
     case NEW_YEAR:
-      mode = new NewYear(&display);
+      mode = new NewYear(display);
       break;
     case STARFIELD:
-      mode = new Starfield(&display);
+      mode = new Starfield(display);
+      break;
+    case MATRIX:
+      mode = new Matrix(display);
       break;
     default:
       Serial.print("No mode loaded.\n");
@@ -104,5 +112,5 @@ void mode_step() {
   auto currentMicros = (int64_t) micros();
   microseconds_t dt = (microseconds_t) min(1000000.0, max(1.0, (double) (currentMicros - lastMicros) * config.speed));
   lastMicros = currentMicros;
-  mode->step(dt);
+  mode->loop(dt);
 }
diff --git a/src/mode/Border/Border.h b/src/mode/Border/Border.h
index 46d8403..bd606ea 100644
--- a/src/mode/Border/Border.h
+++ b/src/mode/Border/Border.h
@@ -1,30 +1,32 @@
-#ifndef TEST_H
-#define TEST_H
+#ifndef MODE_BORDER_H
+#define MODE_BORDER_H
 
 #include "mode/Mode.h"
 
-class Border : public Mode<Border> {
+class Border : public Mode {
 
 public:
 
-    explicit Border(Display *display) :
-      Mode(display) {
+    explicit Border(Display &display) :
+        Mode(display) {
       // nothing
     }
 
-    ~Border() override = default;
-
     const char *getName() override {
       return "Border";
     }
 
-    void doStep(microseconds_t dt) override {
-      for (int y = 0; y < display->height; y++) {
-        for (int x = 0; x < display->width; x++) {
-          if (x == 0 || x == display->width - 1 || y == 0 || y == display->height - 1) {
-            display->set(x, y, WHITE);
+protected:
+
+    void draw(Display &display) override {
+      Serial.print("[BORDER] draw\n");
+      for (int y = 0; y < height; y++) {
+        for (int x = 0; x < width; x++) {
+          Serial.printf("[BORDER] draw %d / %d\n", x, y);
+          if (x == 0 || x == width - 1 || y == 0 || y == height - 1) {
+            display.set(x, y, WHITE);
           } else {
-            display->set(x, y, BLACK);
+            display.set(x, y, BLACK);
           }
         }
       }
diff --git a/src/mode/Clock/Clock.h b/src/mode/Clock/Clock.h
index baf86f6..71beac6 100644
--- a/src/mode/Clock/Clock.h
+++ b/src/mode/Clock/Clock.h
@@ -1,43 +1,44 @@
-#ifndef CLOCK_H
-#define CLOCK_H
+#ifndef MODE_CLOCK_H
+#define MODE_CLOCK_H
 
 #include "mode/Mode.h"
 
-class Clock : public Mode<Clock> {
+class Clock : public Mode {
 
 public:
 
-    explicit Clock(Display *display) :
+    explicit Clock(Display &display) :
         Mode(display) {
       // nothing
     }
 
-    ~Clock() override = default;
-
     const char *getName() override {
       return "Clock";
     }
 
-    void doStep(microseconds_t dt) override {
-      tm info{};
-      time_t now;
-      time(&now);
-      localtime_r(&now, &info);
-      bool ok = info.tm_year >= (2023 - 1900);
+protected:
+
+    void step(microseconds_t dt) override {
+      if (realtimeChanged) {
+        markDirty();
+      }
+    }
+
+    void draw(Display &display) override {
+      display.clear();
 
-      display->clear();
       uint8_t x = 2;
-      x += display->print(x, 1, ok ? info.tm_hour / 10 : 13, WHITE);
+      x += display.print(x, 1, realtimeOK ? now.tm_hour / 10 : 13, WHITE);
       x++;
-      x += display->print(x, 1, ok ? info.tm_hour % 10 : 13, WHITE);
-      x += display->print(x, 1, 10, WHITE);
-      x += display->print(x, 1, ok ? info.tm_min / 10 : 13, WHITE);
+      x += display.print(x, 1, realtimeOK ? now.tm_hour % 10 : 13, WHITE);
+      x += display.print(x, 1, 10, WHITE);
+      x += display.print(x, 1, realtimeOK ? now.tm_min / 10 : 13, WHITE);
       x++;
-      x += display->print(x, 1, ok ? info.tm_min % 10 : 13, WHITE);
-      x += display->print(x, 1, 10, WHITE);
-      x += display->print(x, 1, ok ? info.tm_sec / 10 : 13, WHITE);
+      x += display.print(x, 1, realtimeOK ? now.tm_min % 10 : 13, WHITE);
+      x += display.print(x, 1, 10, WHITE);
+      x += display.print(x, 1, realtimeOK ? now.tm_sec / 10 : 13, WHITE);
       x++;
-      x += display->print(x, 1, ok ? info.tm_sec % 10 : 13, WHITE);
+      x += display.print(x, 1, realtimeOK ? now.tm_sec % 10 : 13, WHITE);
     }
 
 };
diff --git a/src/mode/GameOfLife/Cell.h b/src/mode/GameOfLife/Cell.h
index c18e6a3..3b27e8b 100644
--- a/src/mode/GameOfLife/Cell.h
+++ b/src/mode/GameOfLife/Cell.h
@@ -14,7 +14,7 @@ public:
     Color color = BLACK;
 
     void animate(microseconds_t dt) {
-      // TODO "doStep" does not work as expected
+      // TODO fading does not work as expected
       if (alive) {
         fade = doStep(fade, 0.0, 255.0, 200, +dt);
       } else {
diff --git a/src/mode/GameOfLife/GameOfLife.h b/src/mode/GameOfLife/GameOfLife.h
index a354fe0..9761c2e 100644
--- a/src/mode/GameOfLife/GameOfLife.h
+++ b/src/mode/GameOfLife/GameOfLife.h
@@ -1,20 +1,27 @@
-#ifndef GAMEOFLIFE_H
-#define GAMEOFLIFE_H
+#ifndef MODE_GAME_OF_LIFE_H
+#define MODE_GAME_OF_LIFE_H
 
 #include "mode/Mode.h"
-#include "display/Display.h"
 #include "Cell.h"
 
 enum ColorMode {
     BLACK_WHITE, GRAYSCALE, COLOR_FADE, RANDOM_COLOR
 };
 
-class GameOfLife : public Mode<GameOfLife> {
+class GameOfLife : public Mode {
 
 private:
 
     ColorMode colorMode;
 
+    size_t cellsSize;
+
+    Cell *cells;
+
+    Cell *cellsEnd;
+
+    Cell *next;
+
     microseconds_t runtime = 0;
 
     uint8_t steps = 0;
@@ -25,21 +32,19 @@ private:
 
     uint8_t isSteadyCount = 0;
 
-    Cell *cells;
-
-    Cell *next;
-
 public:
 
-    explicit GameOfLife(Display *display, ColorMode colorMode) :
+    explicit GameOfLife(Display &display, ColorMode colorMode) :
         Mode(display),
-        colorMode(colorMode) {
-      cells = (Cell *) malloc(display->pixelCount * sizeof(Cell));
-      for (Cell *cell = cells; cell < cells + display->pixelCount; cell++) {
+        colorMode(colorMode),
+        cellsSize(display.pixelCount * sizeof(Cell)) {
+      cells = (Cell *) malloc(cellsSize);
+      cellsEnd = cells + cellsSize;
+      for (Cell *cell = cells; cell < cells + display.pixelCount; cell++) {
         kill(cell);
       }
-      next = (Cell *) malloc(display->pixelCount * sizeof(Cell));
-      for (Cell *cell = next; cell < next + display->pixelCount; cell++) {
+      next = (Cell *) malloc(cellsSize);
+      for (Cell *cell = next; cell < next + display.pixelCount; cell++) {
         kill(cell);
       }
     }
@@ -69,7 +74,9 @@ public:
       return "???";
     }
 
-    void doStep(microseconds_t dt) override {
+protected:
+
+    void step(microseconds_t dt) override {
       runtime += dt;
       if (runtime >= 500000) {
         runtime = 0;
@@ -85,14 +92,45 @@ public:
           nextGeneration();
         }
       }
-      animate(dt);
+      for (Cell *cell = cells; cell < cellsEnd; cell++) {
+        cell->animate(dt);
+      }
+
+      // TODO don't always markDirty. Be more efficient
+      markDirty();
+    }
+
+    void draw(Display &display) override {
+      Cell *cell = cells;
+      for (int y = 0; y < height; y++) {
+        for (int x = 0; x < width; x++) {
+          uint8_t brightness;
+          switch (colorMode) {
+            case BLACK_WHITE:
+              brightness = cell->alive ? 255 : 0;
+              display.set(x, y, gray(brightness));
+              break;
+            case GRAYSCALE:
+              brightness = (uint8_t) cell->fade;
+              display.set(x, y, gray(brightness));
+              break;
+            case COLOR_FADE:
+              display.set(x, y, {cell->getR(), cell->getG(), cell->getB()});
+              break;
+            case RANDOM_COLOR:
+              display.set(x, y, cell->alive ? cell->color : BLACK);
+              break;
+          }
+          cell++;
+        }
+      }
     }
 
 private:
 
     void randomFill() {
       isSteadyCount = 0;
-      for (Cell *cell = cells; cell < cells + display->pixelCount; cell++) {
+      for (Cell *cell = cells; cell < cellsEnd; cell++) {
         if (random(4) == 0) {
           if (!cell->alive) {
             spawn(cell);
@@ -117,11 +155,11 @@ private:
     }
 
     void nextGeneration() {
-      memcpy(next, cells, display->pixelCount * sizeof(Cell));
+      memcpy(next, cells, cellsSize);
       Cell *src = cells;
       Cell *dst = next;
-      for (int y = 0; y < display->height; y++) {
-        for (int x = 0; x < display->width; x++) {
+      for (int y = 0; y < height; y++) {
+        for (int x = 0; x < width; x++) {
           uint8_t around = countAround(x, y);
           if (src->alive) {
             if (around <= 2 || 6 <= around) {
@@ -134,14 +172,14 @@ private:
           dst++;
         }
       }
-      memcpy(cells, next, display->pixelCount * sizeof(Cell));
+      memcpy(cells, next, cellsSize);
     }
 
     void print() {
       Cell *cell = cells;
-      for (int y = 0; y < display->height; y++) {
+      for (int y = 0; y < height; y++) {
         Serial.print("|");
-        for (int x = 0; x < display->width; x++) {
+        for (int x = 0; x < width; x++) {
           Serial.print(cell->alive ? "x|" : " |");
           cell++;
         }
@@ -150,33 +188,6 @@ private:
       }
     }
 
-    void animate(microseconds_t dt) {
-      Cell *cell = cells;
-      for (int y = 0; y < display->height; y++) {
-        for (int x = 0; x < display->width; x++) {
-          cell->animate(dt);
-          uint8_t brightness;
-          switch (colorMode) {
-            case BLACK_WHITE:
-              brightness = cell->alive ? 255 : 0;
-              display->set(x, y, gray(brightness));
-              break;
-            case GRAYSCALE:
-              brightness = (uint8_t) cell->fade;
-              display->set(x, y, gray(brightness));
-              break;
-            case COLOR_FADE:
-              display->set(x, y, {cell->getR(), cell->getG(), cell->getB()});
-              break;
-            case RANDOM_COLOR:
-              display->set(x, y, cell->alive ? cell->color : BLACK);
-              break;
-          }
-          cell++;
-        }
-      }
-    }
-
     uint8_t countAround(int x, int y) {
       return countIfAlive(x - 1, y - 1) + countIfAlive(x + 0, y - 1) + countIfAlive(x + 1, y - 1) +
              countIfAlive(x - 1, y + 0) + /*                              */ countIfAlive(x + 1, y + 0) +
@@ -184,15 +195,16 @@ private:
     }
 
     uint8_t countIfAlive(int x, int y) {
-      if (x < 0 || y < 0 || x >= display->width || y >= display->height) {
+      if (x < 0 || y < 0 || x >= width || y >= height) {
         return 0;
       }
       return get(x, y)->alive ? 1 : 0;
     }
 
     Cell *get(int x, int y) {
-      return cells + display->width * y + x;
+      return cells + width * y + x;
     }
+
 };
 
 #endif
diff --git a/src/mode/Mode.h b/src/mode/Mode.h
index 349e158..09f5ec5 100644
--- a/src/mode/Mode.h
+++ b/src/mode/Mode.h
@@ -1,12 +1,8 @@
 #ifndef MODE_H
 #define MODE_H
 
-#define TIMER_COUNT 10
-
 #include "BASICS.h"
 #include "display/Display.h"
-#include "Timer.h"
-#include "ModeBase.h"
 
 enum ModeId {
     NONE,
@@ -20,25 +16,121 @@ enum ModeId {
     SPACE_INVADERS,
     NEW_YEAR,
     STARFIELD,
+    MATRIX,
 };
 
-template<typename T>
-class Mode : public ModeBase {
+class Mode {
+
+private:
+
+    struct Timer {
+        millis_t interval;
+        millis_t last;
+    };
+
+    Display &_display;
+
+    bool dirty = true;
+
+    Timer timers[2] = {
+        {0, 0},
+        {0, 0},
+    };
 
 protected:
 
-    static T *instance;
+    const uint8_t width;
+
+    const uint8_t height;
+
+    bool realtimeOK = false;
+
+    bool realtimeChanged = false;
+
+    tm now = {0, 0, 0, 0, 0, 0, 0, 0, 0};
+
+    time_t epoch = 0;
+
+    virtual void tick(uint8_t index, millis_t dt) {};
+
+    virtual void step(microseconds_t dt) {};
+
+    virtual void draw(Display &display) {};
+
+    void timer(uint8_t index, millis_t interval) {
+      if (index >= countof(timers)) {
+        return;
+      }
+      timers[index].interval = interval;
+      timers[index].last = millis();
+    }
+
+    void markDirty() {
+      dirty = true;
+    }
 
 public:
 
-    explicit Mode(Display *display) :
-        ModeBase(display) {
-      instance = (T *) this;
+    explicit Mode(Display &display) :
+        _display(display),
+        width(display.width),
+        height(display.height) {
+      // nothing
+    }
+
+    virtual ~Mode() = default;
+
+    virtual const char *getName() = 0;
+
+    void loop(microseconds_t dt) {
+      Serial.print("[MODE] realtime\n");
+      realtime();
+
+      Serial.print("[MODE] handleTimers\n");
+      handleTimers();
+
+      Serial.print("[MODE] step\n");
+      step(dt);
+
+      if (dirty) {
+        dirty = false;
+        Serial.print("[MODE] draw\n");
+        draw(_display);
+      }
+    }
+
+private:
+
+    void realtime() {
+      time_t tmp;
+      time(&tmp);
+      realtimeOK = tmp > 1600000000;
+      if (realtimeOK) {
+        realtimeChanged = epoch != tmp;
+        if (realtimeChanged) {
+          epoch = tmp;
+          localtime_r(&tmp, &now);
+          now.tm_year += 1900;
+          now.tm_mon += 1;
+        }
+      } else {
+        realtimeChanged = false;
+      }
+    }
+
+    void handleTimers() {
+      millis_t ms = millis();
+      for (Timer *timer = timers; timer < timers + sizeof(timers); timer++) {
+        if (timer->interval > 0) {
+          millis_t dt = ms - timer->last;
+          if (dt >= timer->interval) {
+            timer->last = ms;
+            tick(timer - timers, dt);
+          }
+        }
+      }
     }
 
 };
 
-template<typename T>
-T *Mode<T>::instance = nullptr;
-
 #endif
diff --git a/src/mode/ModeBase.h b/src/mode/ModeBase.h
deleted file mode 100644
index 6623fcc..0000000
--- a/src/mode/ModeBase.h
+++ /dev/null
@@ -1,91 +0,0 @@
-#ifndef MODE_BASE_H
-#define MODE_BASE_H
-
-#define TIMER_COUNT 10
-
-#include "BASICS.h"
-#include "display/Display.h"
-#include "Timer.h"
-
-class ModeBase {
-
-private:
-
-    Timer *timers[TIMER_COUNT]{};
-
-    uint8_t timerCount = 0;
-
-protected:
-
-    Display *display;
-
-public:
-
-    explicit ModeBase(Display *display) :
-        display(display) {
-      for (Timer **timer = timers; timer < timers + TIMER_COUNT; timer++) {
-        *timer = nullptr;
-      }
-    }
-
-    virtual ~ModeBase() {
-      destroyAllTimers();
-    };
-
-    virtual const char *getName() = 0;
-
-    void step(microseconds_t dt) {
-      for (Timer **timer = timers; timer < timers + TIMER_COUNT; timer++) {
-        if (*timer != nullptr) {
-          (*timer)->step(dt);
-        }
-      }
-      doStep(dt);
-    }
-
-protected:
-
-    virtual void doStep(microseconds_t dt) {};
-
-    Timer *createTimer(long long millisecondsInterval, Timer::Callback callback) {
-      for (Timer **timer = timers; timer < timers + TIMER_COUNT; timer++) {
-        if (*timer == nullptr) {
-          *timer = new Timer(millisecondsInterval * 1000, callback);
-          timerCount++;
-          return *timer;
-        }
-      }
-      Serial.printf("ERROR: Cannot create more than %d timers!\n", TIMER_COUNT);
-      return nullptr;
-    }
-
-    bool destroyTimer(Timer *t) {
-      for (Timer **timer = timers; timer < timers + TIMER_COUNT; timer++) {
-        if (*timer == t) {
-          _destroyTimer(timer);
-          return true;
-        }
-      }
-      Serial.printf("ERROR: No such timer.\n");
-      return false;
-    }
-
-    void destroyAllTimers() {
-      for (Timer **timer = timers; timer < timers + TIMER_COUNT; timer++) {
-        if (*timer != nullptr) {
-          _destroyTimer(timer);
-        }
-      }
-    }
-
-private:
-
-    void _destroyTimer(Timer **timer) {
-      timerCount--;
-      free(*timer);
-      *timer = nullptr;
-    }
-
-};
-
-#endif
diff --git a/src/mode/NewYear/Firework.h b/src/mode/NewYear/Firework.h
index 97f8ed3..38865df 100644
--- a/src/mode/NewYear/Firework.h
+++ b/src/mode/NewYear/Firework.h
@@ -11,7 +11,9 @@ class Firework {
         INITIAL, RISE, EXPLODE, SPARKLE
     };
 
-    Display *display{};
+    uint8_t width = 0;
+
+    uint8_t height = 0;
 
     Color color = MAGENTA;
 
@@ -31,17 +33,18 @@ class Firework {
 
 public:
 
-    void init(Display *_display) {
-      this->display = _display;
+    void init(Display &display) {
+      width = display.width;
+      height = display.height;
       reset();
     }
 
     void reset() {
-      position = Vector((double) random(display->width), display->height);
+      position = Vector((double) random(width), height);
       color = randomColor();
       state = INITIAL;
 
-      destinationHeight = display->height / 2.0 + (double) random(5) - 2;
+      destinationHeight = height / 2.0 + (double) random(5) - 2;
       explosionRadius = (double) random(3) + 1;
       sparkleMax = 100;
 
@@ -49,12 +52,12 @@ public:
       sparkle = 0.0;
     }
 
-    void launch() {
+    bool launch() {
       if (state != INITIAL) {
-        Serial.println("ERROR: Cannot start Firework. Already started.");
-        return;
+        return false;
       }
       state = RISE;
+      return true;
     }
 
     void step(microseconds_t dt) {
@@ -81,7 +84,7 @@ public:
         case INITIAL:
           break;
         case RISE:
-          position.y = doStep(position.y, 0.0, display->height, 1000, -dt);
+          position.y = doStep(position.y, 0.0, height, 1000, -dt);
           break;
         case EXPLODE:
           explosion = doStep(explosion, 0.0, explosionRadius, 500, +dt);
@@ -92,42 +95,40 @@ public:
       }
     }
 
-    void draw() {
+    void draw(Display display) {
       switch (state) {
         case INITIAL:
           break;
         case RISE:
-          display->set(position, YELLOW);
+          display.set(position, YELLOW);
           break;
         case EXPLODE:
-          drawParticle(+0.0, +1.0);
-          drawParticle(+0.7, +0.7);
-          drawParticle(+1.0, +0.0);
-          drawParticle(+0.7, -0.7);
-          drawParticle(+0.0, -1.0);
-          drawParticle(-0.7, -0.7);
-          drawParticle(-1.0, +0.0);
-          drawParticle(-0.7, +0.7);
+          drawParticle(display, +0.0, +1.0);
+          drawParticle(display, +0.7, +0.7);
+          drawParticle(display, +1.0, +0.0);
+          drawParticle(display, +0.7, -0.7);
+          drawParticle(display, +0.0, -1.0);
+          drawParticle(display, -0.7, -0.7);
+          drawParticle(display, -1.0, +0.0);
+          drawParticle(display, -0.7, +0.7);
           break;
         case SPARKLE:
-          if (randomBool(2)) drawParticle(+0.0, +1.0);
-          if (randomBool(2)) drawParticle(+0.7, +0.7);
-          if (randomBool(2)) drawParticle(+1.0, +0.0);
-          if (randomBool(2)) drawParticle(+0.7, -0.7);
-          if (randomBool(2)) drawParticle(+0.0, -1.0);
-          if (randomBool(2)) drawParticle(-0.7, -0.7);
-          if (randomBool(2)) drawParticle(-1.0, +0.0);
-          if (randomBool(2)) drawParticle(-0.7, +0.7);
+          if (randomBool(2)) drawParticle(display, +0.0, +1.0);
+          if (randomBool(2)) drawParticle(display, +0.7, +0.7);
+          if (randomBool(2)) drawParticle(display, +1.0, +0.0);
+          if (randomBool(2)) drawParticle(display, +0.7, -0.7);
+          if (randomBool(2)) drawParticle(display, +0.0, -1.0);
+          if (randomBool(2)) drawParticle(display, -0.7, -0.7);
+          if (randomBool(2)) drawParticle(display, -1.0, +0.0);
+          if (randomBool(2)) drawParticle(display, -0.7, +0.7);
           break;
       }
     }
 
-    void drawParticle(double x, double y) {
-      display->set(position.plus(x * explosion, y * explosion), color);
-    }
+private:
 
-    bool isAlive() {
-      return state != INITIAL;
+    void drawParticle(Display display, double x, double y) {
+      display.set(position.plus(x * explosion, y * explosion), color);
     }
 
 };
diff --git a/src/mode/NewYear/NewYear.h b/src/mode/NewYear/NewYear.h
index 1e357ec..cda6af5 100644
--- a/src/mode/NewYear/NewYear.h
+++ b/src/mode/NewYear/NewYear.h
@@ -1,145 +1,225 @@
-#ifndef NEWYEAR_H
-#define NEWYEAR_H
+#ifndef MODE_NEW_YEAR_H
+#define MODE_NEW_YEAR_H
 
 #define MAX_FIREWORKS                 10
 
 #include "mode/Mode.h"
 #include "Firework.h"
 
-class NewYear : public Mode<NewYear> {
+class NewYear : public Mode {
 
-    Firework fireworksBegin[MAX_FIREWORKS];
-    Firework *fireworksEnd = fireworksBegin + MAX_FIREWORKS;
+private:
 
-    void launch(Timer *timer, uint32_t counter, uint32_t currentCount) {
-      for (Firework *firework = fireworksBegin; firework < fireworksEnd; firework++) {
-        if (!firework->isAlive()) {
-          firework->launch();
+    Firework fireworks[MAX_FIREWORKS];
+
+    int8_t lastSecond = -1;
+
+    millis_t lastSecondMillis = 0;
+
+    uint8_t days = 0;
+
+    uint8_t level = 0;
+
+public:
+
+    explicit NewYear(Display &display) :
+        Mode(display) {
+      timer(0, 500);
+      for (auto &firework: fireworks) {
+        firework.init(display);
+      }
+    }
+
+    const char *getName() override {
+      return "NewYear";
+    }
+
+protected:
+
+    void step(microseconds_t dt) override {
+      if (!realtimeOK) {
+        setMode(NO_TIME);
+      } else if (now.tm_mon != 1 || now.tm_mday != 1 || now.tm_hour != 0) {
+        days = getDayCountForYear(now.tm_year) - now.tm_yday - 1;
+        if (days == 0) {
+          loopLastDay();
+        } else {
+          loopMultipleDays();
+        }
+      } else {
+        setMode(FIREWORK);
+        for (auto &firework: fireworks) {
+          firework.step(dt);
+        }
+      }
+    }
+
+    void loopLastDay() {
+      setMode(LAST_DAY);
+      int levelTmp = getLevel();
+      if (level != levelTmp) {
+        level = levelTmp;
+        markDirty();
+      }
+    }
+
+    void loopMultipleDays() {
+      setMode(MULTIPLE_DAYS);
+      if (realtimeChanged) {
+        markDirty();
+      }
+    }
+
+    void tick(uint8_t index, millis_t dt) override {
+      launch();
+    }
+
+    void draw(Display &display) override {
+      display.clear();
+      if (realtimeOK) {
+        drawNoTime(display);
+      } else if (now.tm_mon == 1 && now.tm_mday == 1 && now.tm_hour == 0) {
+        drawYear(display, now.tm_year + 1900);
+        drawFirework(display);
+      } else {
+        drawCountdown(display, now);
+      }
+    }
+
+private:
+
+    enum State {
+        NO_TIME,
+        MULTIPLE_DAYS,
+        LAST_DAY,
+        FIREWORK,
+    };
+
+    State _state = NO_TIME;
+
+    void setMode(State state) {
+      if (_state != state) {
+        _state = state;
+        markDirty();
+        timer(0, 0);
+        switch (state) {
+          case LAST_DAY:
+            lastSecond = -1;
+            break;
+          case FIREWORK:
+            timer(0, 500);
+            break;
+          default:
+            break;
+        }
+      }
+    }
+
+    int getLevel() {
+      if (lastSecond < 0 || lastSecond != now.tm_sec) {
+        lastSecond = (int8_t) now.tm_sec;
+        lastSecondMillis = millis();
+      }
+      millis_t mils = millis() - lastSecondMillis;
+      int levelTmp = (int) round(32 * mils / 1000.0);
+      return levelTmp;
+    }
+
+    void launch() {
+      for (auto &firework: fireworks) {
+        if (firework.launch()) {
           return;
         }
       }
     }
 
-    int lastSecond = -1;
-
-    unsigned long lastSecondMillis = 0;
-
-    void step(Timer *timer, uint32_t counter, uint32_t currentCount) {
-      tm info{};
-      time_t now;
-      time(&now);
-      localtime_r(&now, &info);
-      info.tm_year += 1900;
-      info.tm_mon += 1;
-      bool ok = info.tm_year >= 2023;
-
-      display->clear();
-      if (!ok) {
-        drawNoTime();
-      } else if (info.tm_mon == 1 && info.tm_mday == 1 && info.tm_hour == 0) {
-        drawYear(counter, info.tm_year + 1900);
-        drawFirework(timer->interval);
-      } else {
-        drawCountdown(info);
-      }
-    }
-
-    void drawNoTime() {
-      uint8_t x = 2;
-      x += display->print(x, 1, 13, WHITE);
-      x++;
-      x += display->print(x, 1, 13, WHITE);
-      x += display->print(x, 1, 10, WHITE);
-      x += display->print(x, 1, 13, WHITE);
-      x++;
-      x += display->print(x, 1, 13, WHITE);
-      x += display->print(x, 1, 10, WHITE);
-      x += display->print(x, 1, 13, WHITE);
-      x++;
-      x += display->print(x, 1, 13, WHITE);
-    }
-
-    void drawCountdown(const tm &time) {
-      int days = getDayCountForYear(time.tm_year) - time.tm_yday - 1;
-
-      int hours = (24 - time.tm_hour - (time.tm_min > 0 || time.tm_sec > 0 ? 1 : 0));
-      int minutes = (60 - time.tm_min - (time.tm_sec > 0 ? 1 : 0)) % 60;
-      int seconds = (60 - time.tm_sec) % 60;
+    void drawCountdown(Display &display, const tm &now) {
+      uint8_t hours = (24 - now.tm_hour - (now.tm_min > 0 || now.tm_sec > 0 ? 1 : 0));
+      uint8_t minutes = (60 - now.tm_min - (now.tm_sec > 0 ? 1 : 0)) % 60;
+      uint8_t seconds = (60 - now.tm_sec) % 60;
 
       uint8_t x = 0;
-
       if (days > 0) {
-        drawDay(days, &x);
-        x += display->print(x, 1, 10, WHITE);
+        drawDay(display, days, &x);
+        x += display.print(x, 1, 10, WHITE);
       } else {
         x += 2;
       }
-      drawHour(days, hours, &x);
-      x += display->print(x, 1, 10, WHITE);
-      draw2Digit(minutes, &x);
+      drawHour(display, days, hours, &x);
+      x += display.print(x, 1, 10, WHITE);
+      draw2Digit(display, minutes, &x);
       if (days <= 0) {
-        x += display->print(x, 1, 10, WHITE);
-        draw2Digit(seconds, &x);
-        drawSubSecondsBar(time.tm_sec);
+        x += display.print(x, 1, 10, WHITE);
+        draw2Digit(display, seconds, &x);
+        drawSubSecondsBar(display);
       } else {
-        drawSecondsBar(seconds);
+        drawSecondsBar(display, seconds);
       }
     }
 
-    void drawDay(int days, uint8_t *x) {
+    static void drawNoTime(Display &display) {
+      uint8_t x = 2;
+      x += display.print(x, 1, 13, WHITE);
+      x++;
+      x += display.print(x, 1, 13, WHITE);
+      x += display.print(x, 1, 10, WHITE);
+      x += display.print(x, 1, 13, WHITE);
+      x++;
+      x += display.print(x, 1, 13, WHITE);
+      x += display.print(x, 1, 10, WHITE);
+      x += display.print(x, 1, 13, WHITE);
+      x++;
+      x += display.print(x, 1, 13, WHITE);
+    }
+
+    static void drawDay(Display &display, int days, uint8_t *x) {
       if (days > 100) {
-        *x += display->print(*x, 1, days / 100, WHITE);
+        *x += display.print(*x, 1, days / 100, WHITE);
       } else {
         *x += 3;
       }
       (*x)++;
 
       if (days > 10) {
-        *x += display->print(*x, 1, days / 10 % 10, WHITE);
+        *x += display.print(*x, 1, days / 10 % 10, WHITE);
       } else {
         *x += 3;
       }
       (*x)++;
 
-      *x += display->print(*x, 1, days % 10, WHITE);
+      *x += display.print(*x, 1, days % 10, WHITE);
     }
 
-    void drawHour(int days, int hours, uint8_t *x) {
+    static void drawHour(Display &display, int days, int hours, uint8_t *x) {
       if (days > 0 || hours >= 10) {
-        *x += display->print(*x, 1, hours / 10, WHITE);
+        *x += display.print(*x, 1, hours / 10, WHITE);
       } else {
         *x += 3;
       }
       (*x)++;
-      *x += display->print(*x, 1, hours % 10, WHITE);
+      *x += display.print(*x, 1, hours % 10, WHITE);
     }
 
-    void draw2Digit(int value, uint8_t *x) {
-      *x += display->print(*x, 1, value / 10, WHITE);
+    static void draw2Digit(Display &display, int value, uint8_t *x) {
+      *x += display.print(*x, 1, value / 10, WHITE);
       (*x)++;
-      *x += display->print(*x, 1, value % 10, WHITE);
+      *x += display.print(*x, 1, value % 10, WHITE);
     }
 
-    void drawSecondsBar(int seconds) {
+    static void drawSecondsBar(Display &display, int seconds) {
       for (int pos = 0; pos < 30; pos++) {
         if (pos <= seconds - 30) {
-          display->set(pos + 1, 7, GREEN);
+          display.set(pos + 1, 7, GREEN);
         } else if (pos <= seconds) {
-          display->set(pos + 1, 7, RED);
+          display.set(pos + 1, 7, RED);
         }
       }
     }
 
-    void drawSubSecondsBar(const int second) {
-      if (lastSecond < 0 || lastSecond != second) {
-        lastSecond = second;
-        lastSecondMillis = millis();
-      }
-      unsigned long mils = millis() - lastSecondMillis;
-      int level = (int) round(32 * mils / 1000.0);
+    void drawSubSecondsBar(Display &display) const {
       for (int pos = 0; pos < 32; pos++) {
         if (pos < 32 - level) {
-          display->set(pos, 7, GREEN);
+          display.set(pos, 7, GREEN);
         }
       }
     }
@@ -152,43 +232,23 @@ class NewYear : public Mode<NewYear> {
       return 365;
     }
 
-    void drawYear(uint32_t counter, int year) {
+    static void drawYear(Display &display, int year) {
       uint8_t x = 8;
-      x += display->print(x, 1, year / 1000 % 10, counter % 64 != 0 ? WHITE : BLACK);
+      x += display.print(x, 1, year / 1000 % 10, WHITE);
       x++;
-      x += display->print(x, 1, year / 100 % 10, counter % 64 != 1 ? WHITE : BLACK);
+      x += display.print(x, 1, year / 100 % 10, WHITE);
       x++;
-      x += display->print(x, 1, year / 10 % 10, counter % 64 != 2 ? WHITE : BLACK);
+      x += display.print(x, 1, year / 10 % 10, WHITE);
       x++;
-      x += display->print(x, 1, year / 1 % 10, counter % 64 != 3 ? WHITE : BLACK);
+      x += display.print(x, 1, year / 1 % 10, WHITE);
     }
 
-    void drawFirework(microseconds_t dt) const {
-      for (auto *firework = (Firework *) fireworksBegin; firework < fireworksEnd; firework++) {
-        if (firework->isAlive()) {
-          firework->step(dt);
-          firework->draw();
-        }
+    void drawFirework(Display &display) {
+      for (auto &firework: fireworks) {
+        firework.draw(display);
       }
     }
 
-public:
-
-    explicit NewYear(Display *display) :
-        Mode(display) {
-      createTimer(500, [](Timer *timer, uint32_t counter, uint32_t currentCount) { instance->launch(timer, counter, currentCount); });
-      createTimer(50, [](Timer *timer, uint32_t counter, uint32_t currentCount) { instance->step(timer, counter, currentCount); });
-      for (Firework *firework = fireworksBegin; firework < fireworksEnd; firework++) {
-        firework->init(display);
-      }
-    }
-
-    ~NewYear() override = default;
-
-    const char *getName() override {
-      return "NewYear";
-    }
-
 };
 
 #endif
diff --git a/src/mode/Pong/Pong.h b/src/mode/Pong/Pong.h
index 21e8708..3cbc53d 100644
--- a/src/mode/Pong/Pong.h
+++ b/src/mode/Pong/Pong.h
@@ -1,11 +1,11 @@
-#ifndef PONG_H
-#define PONG_H
+#ifndef MODE_PONG_H
+#define MODE_PONG_H
 
 #include "mode/Mode.h"
 #include "Player.h"
 #include "display/Vector.h"
 
-class Pong : public Mode<Pong> {
+class Pong : public Mode {
 
 private:
 
@@ -25,34 +25,45 @@ private:
 
     microseconds_t timeout = 0;
 
-    void resetPlayer() {
-      player0.size = 3;
-      player0.score = 0;
-      player0.position = (display->height - player0.size) / 2;
-      player1.size = 3;
-      player1.score = 0;
-      player1.position = (display->height - player1.size) / 2;
+public:
+
+    explicit Pong(Display &display) :
+        Mode(display),
+        position(width / 2.0, height / 2.0),
+        velocity(Vector::polar(random(360), exp10(1))) {
+      timer(0, 100);
+      spawnBall(random(2) == 0 ? -1 : +1);
+      resetPlayer();
     }
 
-    void tick(Timer *timer, uint32_t totalCount, uint32_t currentCount) {
+    const char *getName() override {
+      return "Pong";
+    }
+
+protected:
+
+    void tick(uint8_t index, millis_t dt) override {
       switch (status) {
         case SCORE:
-          timeout -= currentCount * timer->interval;
+          timeout -= dt;
           if (timeout <= 0) {
             status = PLAY;
           }
           break;
         case PLAY:
           position = position.plus(velocity);
-          player0.randomMove(display->height);
-          player1.randomMove(display->height);
+          player0.randomMove(height);
+          player1.randomMove(height);
           paddleBounce();
           checkScoring();
           topBottomBounce();
-          draw();
+
+          // TODO don't always markDirty. Be more efficient
+          markDirty();
+
           break;
         case OVER:
-          timeout -= currentCount * timer->interval;
+          timeout -= dt;
           if (timeout <= 0) {
             resetPlayer();
             status = SCORE;
@@ -62,15 +73,54 @@ private:
       }
     }
 
+    void draw(Display &display) override {
+      display.clear();
+      switch (status) {
+        case SCORE:
+          display.print(1, 1, player0.score, GREEN);
+          display.print(width - 1 - DISPLAY_CHAR_WIDTH, 1, player1.score, RED);
+          break;
+        case PLAY:
+          for (int i = 0; i < player0.size; ++i) {
+            display.set(1, (uint8_t) round(player0.position) + i, GREEN);
+          }
+          for (int i = 0; i < player1.size; ++i) {
+            display.set(width - 2, (uint8_t) round(player1.position) + i, RED);
+          }
+          display.set((uint8_t) round(position.x), (uint8_t) round(position.y), WHITE);
+          break;
+        case OVER:
+          if (player0.score > player1.score) {
+            display.print(1, 1, 11, GREEN);
+            display.print(width - 1 - DISPLAY_CHAR_WIDTH, 1, 12, RED);
+          } else if (player0.score < player1.score) {
+            display.print(1, 1, 12, RED);
+            display.print(width - 1 - DISPLAY_CHAR_WIDTH, 1, 11, GREEN);
+          }
+          break;
+      }
+    }
+
+private:
+
+    void resetPlayer() {
+      player0.size = 3;
+      player0.score = 0;
+      player0.position = (height - player0.size) / 2;
+      player1.size = 3;
+      player1.score = 0;
+      player1.position = (height - player1.size) / 2;
+    }
+
     void topBottomBounce() {
-      position = position.bounceInBox(display->width, display->height);
+      position = position.bounceInBox(width, height);
     }
 
     void checkScoring() {
       if (position.x < 0) {
         player1.score++;
         spawnBall(+1);
-      } else if (position.x >= display->width) {
+      } else if (position.x >= width) {
         player0.score++;
         spawnBall(-1);
       }
@@ -84,67 +134,21 @@ private:
       if (position.x == 1 && player0.position <= position.y && position.y < player0.position + player0.size) {
         velocity.x = -velocity.x;
         position.x = 3;
-      } else if (position.x == display->width - 2 && player1.position <= position.y && position.y < player1.position + player1.size) {
+      } else if (position.x == width - 2 && player1.position <= position.y && position.y < player1.position + player1.size) {
         velocity.x = -velocity.x;
-        position.x = display->width - 4;
+        position.x = width - 4;
       }
     }
 
     void spawnBall(int direction) {
-      position.x = (double) display->width / 2.0;
-      position.y = (double) display->height / 2.0;
+      position.x = (double) width / 2.0;
+      position.y = (double) height / 2.0;
       velocity.x = direction;
       velocity.y = 0;
       status = SCORE;
       timeout = 2000000;
     }
 
-    void draw() {
-      display->clear();
-      switch (status) {
-        case SCORE:
-          display->print(1, 1, player0.score, GREEN);
-          display->print(display->width - 1 - DISPLAY_CHAR_WIDTH, 1, player1.score, RED);
-          break;
-        case PLAY:
-          for (int i = 0; i < player0.size; ++i) {
-            display->set(1, (uint8_t) round(player0.position) + i, GREEN);
-          }
-          for (int i = 0; i < player1.size; ++i) {
-            display->set(display->width - 2, (uint8_t) round(player1.position) + i, RED);
-          }
-          display->set((uint8_t) round(position.x), (uint8_t) round(position.y), WHITE);
-          break;
-        case OVER:
-          if (player0.score > player1.score) {
-            display->print(1, 1, 11, GREEN);
-            display->print(display->width - 1 - DISPLAY_CHAR_WIDTH, 1, 12, RED);
-          } else if (player0.score < player1.score) {
-            display->print(1, 1, 12, RED);
-            display->print(display->width - 1 - DISPLAY_CHAR_WIDTH, 1, 11, GREEN);
-          }
-          break;
-      }
-    }
-
-public:
-
-    explicit Pong(Display *display) :
-        Mode(display),
-        position(display->width / 2.0, display->height / 2.0),
-        velocity(Vector::polar(random(360), exp10(1))) {
-      instance = this;
-      createTimer(100, [](Timer *timer, uint32_t counter, uint32_t currentCount) { instance->tick(timer, counter, currentCount); });
-      spawnBall(random(2) == 0 ? -1 : +1);
-      resetPlayer();
-    }
-
-    ~Pong() override = default;
-
-    const char *getName() override {
-      return "Pong";
-    }
-
 };
 
 #endif
diff --git a/src/mode/SpaceInvaders/SpaceInvaders.h b/src/mode/SpaceInvaders/SpaceInvaders.h
index ec004a9..d4f76c9 100644
--- a/src/mode/SpaceInvaders/SpaceInvaders.h
+++ b/src/mode/SpaceInvaders/SpaceInvaders.h
@@ -1,5 +1,5 @@
-#ifndef SPACEINVADERS_H
-#define SPACEINVADERS_H
+#ifndef MODE_SPACE_INVADERS_H
+#define MODE_SPACE_INVADERS_H
 
 #define ROCKET_MAX 20
 
@@ -18,7 +18,7 @@ struct Invader {
     uint8_t y;
 };
 
-class SpaceInvaders : public Mode<SpaceInvaders> {
+class SpaceInvaders : public Mode {
 
 private:
 
@@ -45,10 +45,10 @@ private:
 
 public:
 
-    explicit SpaceInvaders(Display *display) :
+    explicit SpaceInvaders(Display &display) :
         Mode(display),
-        invadersCountX(display->width / 3),
-        invadersCountY(display->height / 4) {
+        invadersCountX(width / 3),
+        invadersCountY(height / 4) {
 
       swarmBegin = (Invader *) malloc(sizeof(Invader) * invadersCountX * invadersCountY);
       swarmEnd = swarmBegin + invadersCountX * invadersCountY;
@@ -68,24 +68,37 @@ public:
       return "Space Invaders";
     }
 
-    void doStep(microseconds_t dt) override {
+protected:
+
+    void step(microseconds_t dt) override {
       stepRockets(dt);
       stepInvaders(dt);
       stepHero(dt);
 
-      draw();
-
       collide();
       if (invadersAlive == 0) {
         Serial.println("WINNER!");
         reset();
       }
-      if (swarmY + (invadersCountY - 1) * 2 >= display->height - 1) { // TODO this is only correct if there still are any invaders in the last row (otherwise we "Game Over" too early)
+      // TODO this is only correct if there still are any invaders in the last row (otherwise we "Game Over" too early)
+      if (swarmY + (invadersCountY - 1) * 2 >= height - 1) {
         Serial.println("GAME OVER");
         reset();
       }
+
+      // TODO don't always markDirty. Be more efficient
+      markDirty();
     }
 
+    void draw(Display &display) override {
+      display.clear();
+      drawInvaders(display);
+      drawRockets(display);
+      drawHero(display);
+    }
+
+private:
+
     void stepRockets(microseconds_t dt) {
       rocketRuntime += dt;
       if (rocketRuntime > 200000) {
@@ -146,7 +159,7 @@ public:
           }
         } else {
           heroX++;
-          if (heroX >= display->width - 2 || randomBool(20)) {
+          if (heroX >= width - 2 || randomBool(20)) {
             heroLeft = true;
           }
         }
@@ -164,7 +177,7 @@ public:
         if (!rocket->alive && rocket->flash == 0) {
           rocket->alive = true;
           rocket->x = heroX;
-          rocket->y = display->height - 2;
+          rocket->y = height - 2;
         }
       }
     }
@@ -195,47 +208,40 @@ public:
              && swarmX + invader->x * 3 + 1 >= rocket->x;
     }
 
-    void draw() {
-      display->clear();
-      drawInvaders();
-      drawRockets();
-      drawHero();
-    }
-
-    void drawInvaders() {
+    void drawInvaders(Display &display) {
       for (Invader *invader = swarmBegin; invader < swarmEnd; invader++) {
         if (invader->alive) {
-          display->set(swarmX + invader->x * 3 + 0, swarmY + invader->y * 2, RED);
-          display->set(swarmX + invader->x * 3 + 1, swarmY + invader->y * 2, RED);
+          display.set(swarmX + invader->x * 3 + 0, swarmY + invader->y * 2, RED);
+          display.set(swarmX + invader->x * 3 + 1, swarmY + invader->y * 2, RED);
         }
       }
     }
 
-    void drawRockets() {
+    void drawRockets(Display &display) {
       for (Rocket *rocket = rocketsBegin; rocket < rocketsEnd; rocket++) {
         if (rocket->alive) {
-          display->set(rocket->x, rocket->y, YELLOW);
+          display.set(rocket->x, rocket->y, YELLOW);
         } else if (rocket->flash > 0) {
-          display->set(rocket->x - 1, rocket->y - 1, gray(rocket->flash));
-          display->set(rocket->x - 1, rocket->y + 1, gray(rocket->flash));
-          display->set(rocket->x + 0, rocket->y + 0, gray(rocket->flash));
-          display->set(rocket->x + 1, rocket->y + 1, gray(rocket->flash));
-          display->set(rocket->x + 1, rocket->y - 1, gray(rocket->flash));
+          display.set(rocket->x - 1, rocket->y - 1, gray(rocket->flash));
+          display.set(rocket->x - 1, rocket->y + 1, gray(rocket->flash));
+          display.set(rocket->x + 0, rocket->y + 0, gray(rocket->flash));
+          display.set(rocket->x + 1, rocket->y + 1, gray(rocket->flash));
+          display.set(rocket->x + 1, rocket->y - 1, gray(rocket->flash));
         }
       }
     }
 
-    void drawHero() {
-      display->set(heroX - 1, display->height - 1, BLUE);
-      display->set(heroX + 0, display->height - 1, BLUE);
-      display->set(heroX + 1, display->height - 1, BLUE);
+    void drawHero(Display &display) {
+      display.set(heroX - 1, height - 1, BLUE);
+      display.set(heroX + 0, height - 1, BLUE);
+      display.set(heroX + 1, height - 1, BLUE);
     }
 
     void reset() {
       heroRuntime = 0;
       heroLeft = false;
       heroShoot = 0;
-      heroX = display->width / 2;
+      heroX = width / 2;
 
       rocketRuntime = 0;
       for (Rocket *rocket = rocketsBegin; rocket < rocketsEnd; rocket++) {
diff --git a/src/mode/Starfield/Starfield.h b/src/mode/Starfield/Starfield.h
index da409bc..735655e 100644
--- a/src/mode/Starfield/Starfield.h
+++ b/src/mode/Starfield/Starfield.h
@@ -1,11 +1,11 @@
-#ifndef MEDIATABLE_STARFIELD_H
-#define MEDIATABLE_STARFIELD_H
+#ifndef MODE_STARFIELD_H
+#define MODE_STARFIELD_H
 
 #include "mode/Mode.h"
 
 #define STAR_COUNT    20
 
-class Starfield : public Mode<Starfield> {
+class Starfield : public Mode {
 
 private:
 
@@ -15,12 +15,12 @@ private:
 
 public:
 
-    explicit Starfield(Display *display) :
+    explicit Starfield(Display &display) :
         Mode(display),
-        center(display->width / 2.0, display->height / 2.0) {
+        center(width / 2.0, height / 2.0) {
       for (auto &star: stars) {
-        star.x = random(display->width);
-        star.y = random(display->height);
+        star.x = random(width);
+        star.y = random(height);
       }
     }
 
@@ -28,16 +28,26 @@ public:
       return "Starfield";
     }
 
-    void doStep(microseconds_t dt) override {
-      display->clear();
+protected:
+
+    void step(microseconds_t dt) override {
       for (auto &star: stars) {
         const Vector velocity = star.minus(center).multiply((double) dt / 200000.0);
         star = star.plus(velocity);
-        if (star.x < 0 || star.x >= display->width || star.y < 0 || star.y >= display->height) {
+        if (star.x < 0 || star.x >= width || star.y < 0 || star.y >= height) {
           star = center.plus(Vector::polar(random(360), 1));
         }
-        uint8_t brightness = (uint8_t) round(255.0 * star.minus(center).length / (display->width / 2.0));
-        display->set(star, gray(brightness));
+      }
+
+      // TODO don't always markDirty. Be more efficient
+      markDirty();
+    }
+
+    void draw(Display &display) override {
+      display.clear();
+      for (auto &star: stars) {
+        uint8_t brightness = (uint8_t) round(255.0 * star.minus(center).length / (width / 2.0));
+        display.set(star, gray(brightness));
       }
     }
 
diff --git a/src/mode/Timer.h b/src/mode/Timer.h
deleted file mode 100644
index 37bf9f2..0000000
--- a/src/mode/Timer.h
+++ /dev/null
@@ -1,42 +0,0 @@
-#ifndef TIMER_H
-#define TIMER_H
-
-#include "BASICS.h"
-
-class Timer {
-
-public:
-
-    typedef void (*Callback)(Timer *timer, uint32_t counter, uint32_t currentCount);
-
-private:
-
-    Callback callback;
-
-    microseconds_t accu = 0;
-
-    uint32_t totalCount = 0;
-
-public:
-
-    microseconds_t interval;
-
-    Timer(microseconds_t interval, Callback callback) :
-      callback(callback),
-      interval(interval) {
-      // nothing
-    }
-
-    void step(microseconds_t dt) {
-      accu += dt;
-      if (accu >= interval) {
-        uint32_t currentCount = accu / interval;
-        totalCount += currentCount;
-        accu = accu % interval;
-        callback(this, totalCount, currentCount);
-      }
-    }
-
-};
-
-#endif
diff --git a/src/server.cpp b/src/server.cpp
index d95ca3f..c89d329 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -113,5 +113,5 @@ void web_fps_off() {
 
 void redirect() {
   server.sendHeader("location", "/");
-  server.send(302, "text/plain", "ok");
+  server.send(302, "text/plain", "realtimeOK");
 }