exp^drop

A retro 80s-styled browser puzzle game where tiles with power-of-two values fall into a grid. Match equal tiles to merge them and climb to higher values!

Agent-assisted development — built from zero with Claude.

Gameplay

• Board: 5 tiles wide x 6 tiles tall
• Tiles: Each tile occupies a 2x2 cell area, displaying powers of two (2, 4, 8, 16...)
• Movement: Tiles move in 2-cell increments to stay grid-aligned

Merge Rules

Tiles merge only when touching tiles of equal value (orthogonally adjacent):

• The newly placed tile absorbs ALL matching neighbors simultaneously
• Each absorbed tile increases the value by one level
• Example: An 8 touching two other 8s becomes 32 (8 -> 16 -> 32)

Merge Animation Sequence

1. Matching tiles get pulled/sucked into the new tile
2. The tile's value updates to show the new number
3. Pop animation on the upgraded tile
4. Gravity pulls the tile down
5. Chain continues if new matches are found

Dynamic Spawning

• Mostly 2s and 4s spawn, with rare 8/16/32 surprises from the very start
• Higher values unlock as you create them on the board — but the top tiers never spawn directly; the last few doublings must be earned by merging
• Higher values spawn less frequently (sliding scale); small tiles keep spawning no matter how far you progress
• Tiles start slow and fall a little faster with every new highest value you create (850ms easing toward 450ms) — gentle pacing, not a race
• Game over when any column stacks to the top of the board

Scoring

• Base points = resulting tile value
• Multi-merge bonus: Absorbing multiple tiles multiplies points (2x, 3x, 4x...)
• Combo bonus: Chain merges increase multiplier (1x, 1.5x, 2x, 2.5x...)

Controls

Keyboard:

• Arrow Left / J: Move left
• Arrow Right / L: Move right
• Arrow Down / K / Space: Hard drop
• P / Escape: Pause
• R: Restart

Mobile Touch:

• Tap on board (left/right of tile): Tile slides to that column with animation, then drops
• Tap on tile: Hard drop
• Tap below tile: Hard drop
• Drag left/right: Move tile by columns (grid-aligned)
• Pause button: Tap "PAUSE"/"CONTINUE" button in top-right corner
• Restart button: Tap "RESTART" on game over screen

Note: Touch-to-drop uses a smooth 120ms slide animation. Tiles move in discrete column steps during drag.

Running the Game

Option 1: Download Release

Download the latest release from Releases, extract, and open index.html in your browser or serve with any static file server:

# Using Python
python -m http.server 8080

# Using Node.js
npx serve .

Option 2: Docker

# Using pre-built image
docker run -p 8080:80 ghcr.io/coredump/exp-drop:latest

# Or using Docker Compose
docker compose up

# Or build locally
docker build -t exp-drop .
docker run -p 8080:80 exp-drop

Then open http://localhost:8080

Option 3: From Source

With Nix (recommended — pins Node 24 and everything else):

nix develop      # Enter the devshell
npm install
npm run dev      # Development server
npm run build    # Production build
npm run preview  # Preview production build

If you use direnv, direnv allow once and the shell loads automatically whenever you cd into the repo.

Without Nix, install Node 24 yourself and skip the nix develop line.

Configuration

Customize game parameters by editing public/game.config.json:

{
  "gridHeight": 12,
  "spawnWeights": {
    "base2": 45,
    "base4": 40,
    "tierMultiplier": 0.5,
    "minWeight": 5
  },
  "tierWindowSize": 6,
  "spawnLag": 1
}

Parameter	Description
gridHeight	Number of visible rows (default: 12)
spawnWeights.base2	Spawn weight for 2-tiles (default: 45)
spawnWeights.base4	Spawn weight for 4-tiles (default: 40)
spawnWeights.tierMultiplier	Weight decay per tier (default: 0.5)
spawnWeights.minWeight	Minimum spawn weight (default: 5)
tierWindowSize	Tiers kept in spawn pool (default: 6)
spawnLag	Top tiers that never spawn, merge-only (default: 1)
initialMaxSpawnTier	Tiers spawnable from the start (default: 2)

Delete the file to use defaults. Partial configs are supported (unspecified values use defaults).

Tech Stack

• Renderer: PixiJS 8.x (WebGL/WebGPU)
• Build: Vite + TypeScript
• Font: Press Start 2P (Google Fonts)
• Style: 80s Neon aesthetic

Project Structure

public/
  game.config.json          # Game configuration (optional, copied to dist/)
src/
  main.ts                   # Entry point, loading screen
  game/
    Game.ts                 # Main game controller
    Board.ts                # Grid state management
    Tile.ts                 # Tile class with animations
    Physics.ts              # Gravity and merge resolution
    Spawner.ts              # Dynamic weighted tile spawning
    InputHandler.ts         # Keyboard and touch input
  renderer/
    BoardRenderer.ts        # Grid and tile rendering
    UIRenderer.ts           # Score, preview, overlays
  utils/
    constants.ts            # Grid size, colors, timings
    config.ts               # Configuration loader
    SeededRNG.ts            # Deterministic random numbers

Personal software

This is personal software. It was built for one person's use, with help from an AI coding agent, and put online because someone else might find it useful.

It's not a product. There is no support, no roadmap, no promise it keeps working. The level of security is appropriate for how the author uses it. You don't need to worry about that on their behalf. The license is the contract. Everything else here is context.

If that framing is interesting or annoying, the long version is here: On Personal Software

If this doesn't suit your needs, don't use it. No hard feelings.

License

MIT - see LICENSE for details.