Summer Engine MCP guide
How to make games in Goose with Summer Engine
Add Summer Engine as a Goose extension and let a free local model build real games through MCP — scenes, scripts, Play mode, and diagnostics. Summer Engine is the desktop game engine; Goose drives it through MCP with a model running on your own hardware.
Summer is free for MCP use
Download the desktop engine and connect it to your agent. The model runs on your own hardware — no AI subscription, no per-message cost.
Open Goose
Run a free local model on your own GPU. The setup writes the MCP config so {agentLabel} can drive the engine directly.
Launch a real game
The local model writes code. Summer Engine shows the game, runs Play mode, and exports projects for Steam, desktop, mobile, and console pipelines.
Local setup notes
The 2026 specifics.
Add Summer as a Goose extension
Run `goose configure`, choose Add Extension → Command-line Extension, and set the command to `npx -y summer-engine@latest mcp`. In Goose Desktop the same lives under Settings → Extensions.
Point Goose at a local model
`goose configure` → Configure Providers → Ollama with host localhost:11434. Pick a model with native tool calling, like gpt-oss-20b or Qwen3-Coder-30B; Goose’s toolshim mode for non-tool-calling models is slower and less reliable.
Mind the context window
Ollama defaults to a 4k context on GPUs under 24 GB of VRAM — too small for MCP tool schemas. Start it with OLLAMA_CONTEXT_LENGTH=65536, and keep only a couple of extensions enabled so tool schemas leave room for actual work.
Why this matters
Goose runs free on your hardware. Summer Engine shows the game.
A capable local model can operate a real engine through MCP: open scenes, place objects, run the project, and read errors. Your GPU does the thinking — no subscription, no per-token bill, and your prompts never leave your machine.