Summer Engine MCP guide
How to make games in Codex with Summer Engine
Set up Codex CLI with the Summer Engine MCP server so it can operate a running desktop game engine instead of only editing files. Summer Engine is the desktop game engine; Codex CLI is the agent that drives it through MCP.
Summer is free for MCP use
Download the desktop engine and connect it to your agent. You are not paying Summer for the AI calls your existing subscription already covers.
Open Codex CLI
Use the AI editor you already have. The setup command writes the MCP config and installs the Summer game-dev skills.
Launch a real game
The agent writes code. Summer Engine shows the game, runs Play mode, and exports projects for Steam, desktop, mobile, and console pipelines.
Why this matters
Codex CLI writes with your subscription. Summer Engine shows the game.
A chat agent alone can write files. With MCP, Codex CLI gets tools for the running game engine, so it can inspect the project, run commands, and make changes that become playable inside Summer.