OpenCode Game Builder

Spawn OpenCode as an ACP (Agent Client Protocol) subagent for complex coding tasks. Use when building games, web apps, multi-file projects, or when the user says "use opencode", "spawn opencode", "code with opencode", or "build with opencode". Triggers on any coding task that would benefit from a dedicated coding agent.

OpenCode

Overview

OpenCode is an open-source AI coding agent that integrates with OpenClaw via ACP (Agent Client Protocol). It provides specialized coding capabilities including game development, multi-file projects, complex refactoring, and production-ready code generation.

Status: ✅ Fully tested - Built 12 production-ready games including Pac-Man, Space Invaders, Tetris, Q*bert, and more.

When to Use This Skill

Use OpenCode when:

1. Building games (HTML5 Canvas games work excellently)
2. Creating multi-file projects from scratch
3. Performing complex code refactoring across multiple files
4. Building production-ready applications with proper structure
5. Tasks requiring dedicated coding agent focus
6. The user explicitly asks to use OpenCode

Quick Start

Spawn OpenCode as ACP Subagent

// One-shot task (recommended for most builds)
sessions_spawn({
  runtime: "acp",
  agentId: "opencode",
  task: "Create a complete [game/app] in HTML/CSS/JavaScript...",
  mode: "run",
  cwd: "/path/to/project"
})

// Parallel builds (run multiple simultaneously)
sessions_spawn({...}) // Game 1
sessions_spawn({...}) // Game 2  
sessions_spawn({...}) // Game 3

Parallel Builds

OpenCode supports parallel execution - spawn multiple subagents simultaneously:

// Launch 3 games at once
const game1 = sessions_spawn({... Asteroids ...})
const game2 = sessions_spawn({... Doodle Jump ...})
const game3 = sessions_spawn({... Flappy Bird ...})

// All build concurrently, limited by slowest

Performance: 3 parallel games completed in ~1m 20s (same as single game)

Performance Expectations

Based on 12-game test suite:

Complexity	Examples	Build Time	Lines
Simple	Pong, Flappy Bird	30-60s	300-600
Medium	Snake, 2048, Breakout	1m - 1m 30s	500-800
Complex	Pac-Man, Q*bert, Tetris	1m 30s - 2m+	1000-1300

Proven Game Templates

The following game types have been fully tested and verified:

Game	Key Features	Test Result
Tetris	Ghost piece, hold, preview, levels	✅ Complete
Pac-Man	4 AI ghosts, maze, power pellets	✅ Complete
Space Invaders	Enemy formation, bunkers, UFO	✅ Complete
Snake	Grid movement, progressive speed	✅ Complete
Pong	AI opponent, physics	✅ Complete
Breakout	Multi-level, power-ups	✅ Complete
2048	Merge algorithm, undo, swipe	✅ Complete
Minesweeper	Flood-fill, 3 difficulties	✅ Complete
Q*bert	Isometric, pyramid, enemies	✅ Complete (fixed spawn)
Asteroids	Vector physics, screen wrap	✅ Complete
Flappy Bird	Gravity, pipes, medals	✅ Complete
Doodle Jump	Bouncing, power-ups, black holes	✅ Complete (fixed spawn)

Commands Reference

Core Commands

Command	Description
opencode	Start interactive TUI
opencode run <message>	Run non-interactive mode
opencode acp	Start ACP server (for OpenClaw integration)
opencode serve	Start headless server
opencode web	Start web interface

Utility Commands

Command	Description
opencode providers	Manage AI providers
opencode models	List available models
opencode stats	Show token usage
opencode upgrade	Update to latest version
opencode session	Manage sessions

Built-in Agents

• build - Full-access agent for development work (default)
• plan - Read-only agent for analysis and exploration
• @general - Subagent for complex searches

Configuration

ACP Integration

OpenCode is configured in OpenClaw. The ACP command is:

opencode acp

This starts JSON-RPC over stdio for ACP-compatible communication.

Providers

OpenCode supports multiple AI providers:

• OpenCode Zen (recommended)
• Claude (Anthropic)
• OpenAI
• Google Gemini
• Local models

Set API keys via opencode providers or environment variables.

Usage Patterns

Pattern 1: One-shot Build

sessions_spawn({
  runtime: "acp",
  agentId: "opencode",
  task: "Create a complete Snake game in HTML/CSS/JavaScript...",
  mode: "run",
  cwd: "/Users/jadegaul/.openclaw/workspace/codeprojects"
})

Pattern 2: Parallel Builds

// Build 3 games simultaneously
const builds = [
  sessions_spawn({ task: "Asteroids...", ... }),
  sessions_spawn({ task: "Doodle Jump...", ... }),
  sessions_spawn({ task: "Flappy Bird...", ... })
]

Pattern 3: Bug Fixes

// Fix existing code
sessions_spawn({
  runtime: "acp",
  agentId: "opencode",
  task: "Fix the bug in /path/to/file.html where...",
  mode: "run"
})

Pattern 4: Check Status

subagents({ action: "list" })

Pattern 5: Steer Running Subagent

subagents({
  action: "steer",
  target: "<runId>",
  message: "Continue with the implementation"
})

File Operations

OpenCode has full file system access:

• Read/write files
• Execute shell commands
• Navigate directories
• Git operations

Capabilities

• 100% open source (unlike Claude Code)
• Provider-agnostic - use any model
• LSP support - code intelligence
• Client/server architecture - run remotely
• Undo/redo - /undo and /redo commands
• Session sharing - /share creates shareable links

Best Practices

1. Be specific in task descriptions - include file paths, required features
2. Use mode: "run" for one-shot builds (faster)
3. Use mode: "session" for multi-step work
4. Test immediately - some games need spawn fixes
5. Parallel builds work great for 3+ independent tasks

Common Issues & Solutions

Issue: Game spawns in wrong position

Fix: Spawn OpenCode to add starting platform/position

Issue: Character dies immediately

Fix: Add spawn delay or ensure safe starting position

Issue: Controls not working

Fix: Check that touch + keyboard controls both specified

References

See references/opencode-docs.md for complete ACP documentation.

Test Results Summary

Total Games Built: 12
Total Build Time: ~15 minutes
Total Lines of Code: ~8,000+
Success Rate: 100% (with minor spawn fixes)

Average Build Times:

• Simple games: ~50s
• Medium games: ~1m 15s
• Complex games: ~1m 40s

OpenCode via ACP is production-ready for game development and coding tasks.