Summer Engine MCP guide
How to make games in LM Studio with Summer Engine
Use LM Studio as a free local MCP host: download a model, connect Summer Engine, and build playable games with no AI subscription. Summer Engine is the desktop game engine; LM Studio 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 LM Studio
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.
LM Studio is the whole stack
LM Studio is both the model runtime and an MCP host. The setup command writes ~/.lmstudio/mcp.json; toggle the summer-engine server on in the Program tab, and every engine call shows a confirmation dialog you can review before it runs.
Raise the context before you build
Models load with the context length baked into their metadata — often around 4k, which MCP tool schemas overflow silently. Set 32k or more when loading the model, and keep KV-cache quantization off for long agent sessions.
Models that hold up
gpt-oss-20b is the safe default on 12–16 GB of VRAM; Qwen3-Coder-30B and Gemma 4 27B are the 24 GB picks. On Apple Silicon, prefer the MLX builds — faster and more memory-efficient in long agentic loops.
Why this matters
LM Studio 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.