following flutter pattern for examples

example/lib/main.dart

@@ -0,0 +1,52 @@
+import 'dart:math' as math;
+import 'dart:ui';
+
+import 'package:flame/anchor.dart';
+import 'package:flame/components/component.dart';
+import 'package:flame/game.dart';
+import 'package:flame/palette.dart';
+import 'package:flutter/material.dart';
+
+void main() => runApp(new MyGame().widget);
+
+class Palette {
+  static const PaletteEntry white = BasicPalette.white;
+  static const PaletteEntry red = PaletteEntry(Color(0xFFFF0000));
+  static const PaletteEntry blue = PaletteEntry(Color(0xFF0000FF));
+}
+
+class Square extends PositionComponent {
+  static const SPEED = 0.25;
+
+  Square(double size) {
+    width = height = size;
+    anchor = Anchor.center;
+  }
+
+  @override
+  void resize(Size size) {
+    x = size.width / 2;
+    y = size.height / 2;
+  }
+
+  @override
+  void render(Canvas c) {
+    prepareCanvas(c);
+
+    c.drawRect(Rect.fromLTWH(0, 0, width, height), Palette.white.paint);
+    c.drawRect(Rect.fromLTWH(0, 0, 3, 3), Palette.red.paint);
+    c.drawRect(Rect.fromLTWH(width / 2, height / 2, 3, 3), Palette.blue.paint);
+  }
+
+  @override
+  void update(double t) {
+    angle += SPEED * t;
+    angle %= (2 * math.pi);
+  }
+}
+
+class MyGame extends BaseGame {
+  MyGame() {
+    add(new Square(64.0));
+  }
+}