Challenges

Create a complete Mario-style side-scrolling platformer as a single self-contained HTML file.

REQUIRED FEATURES:
1. Canvas-based rendering, full-window (maintains 16:9 ratio)
2. Player character: humanoid figure drawn with canvas primitives (body, head, arms, legs) with running animation (leg cycle)
3. Smooth physics: gravity (0.5), horizontal acceleration (0.3, max 5), friction (0.85), jump velocity (-10)
4. Variable jump height: hold jump button = jump higher (released early = short hop), max 300ms hold
5. Controls: Arrow keys / WASD (left/right/jump), Space also jumps
6. Touch controls: left/right buttons on bottom-left, jump button on bottom-right
7. Tile-based level design with at least 3 scrolling screens worth of content (3000px+ wide)
8. Tile types: empty, solid brick (brown with brick pattern), question block (yellow with ?), ground (brown with grass top), pipe (green, acts as solid + decoration)
9. Question blocks contain coins or power-up (super mushroom that makes player grow)
10. Collectible coins scattered through level (100 points each), floating with spin animation
11. Enemies: Goomba-like (walking back and forth, stomp to kill), Koopa-like (in shell, kick shell), flying enemies (patrol horizontally)
12. Player stomps enemy from above = enemy flattened (player bounces up). Side/below contact = player takes damage
13. Player has 3 health (displayed as hearts in HUD). Hit = brief invincibility (flashing, 2 seconds)
14. Level end: flagpole (police line tape style or classic flag). Touch it = win!
15. Moving camera follows player horizontally (never scrolls back left)
16. Parallax background: sky gradient with clouds (slow scroll), mountains (medium scroll), foreground
17. Pits/death zones: gaps in ground that player can fall into (instant death)
18. Start screen: game title + "Press Space to start" + simple controls legend
19. Pause: Escape or P
20. Game over: "GAME OVER", score, "Press Space to retry"
21. Win screen: "YOU WIN!", final score with coin bonus, "Press Space to play again"
22. Score display + coin counter + lives/hearts in HUD

AUDIO:
23. Web Audio API: jump (short ascending tone), coin collect (two-note chime), stomp enemy (thud), power-up (ascending arpeggio), death (descending), win (celebration jingle), background music (simple looping melody using oscillators)

VISUAL:
24. Pixel-art aesthetic achieved through canvas primitives (no sprites)
25. 16×16 pixel tile grid, scaled 3x for play
26. Bright, colorful palette (NES-inspired blues, greens, browns, reds)
27. Player has hat and mustache (Mario-inspired but not identical)

CODE:
28. Single HTML file, vanilla JS, Canvas 2D
29. requestAnimationFrame with delta-time physics
30. Tile map as 2D array, Camera class, Entity class hierarchy, Collision detection (AABB)