Summer Engine MCP guide
How to make games in Gemini CLI and Antigravity with Summer Engine
Gemini CLI was retired for individual accounts in June 2026 and replaced by Antigravity. Connect Antigravity to Summer Engine MCP to create, run, inspect, and improve games in a real desktop engine. Summer Engine is the desktop game engine; Antigravity 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 Antigravity
Use the AI editor you already have. The setup command writes the MCP config and installs the Summer game-dev skills.
Run a Summer game
The agent writes code. Summer Engine shows the Summer game, runs Play mode, and helps inspect errors. Export still requires the target templates and toolchains.
Install
Connect Summer to Antigravity
- 1
Install Summer Engine
Downloads the desktop engine app, about 1 GB. Skip it if Summer Engine is already installed, or if you only need assets and video for a game built in another engine.
- 2
Sign in
Opens your browser once. The CLI and the engine share the session.
- 3
Connect Antigravity
Writes the summer-engine MCP config and installs the Summer game-dev skills.
- 4
Restart and build
In Antigravity open the agent panel's MCP servers view and refresh; summer-engine appears in the list (IDE and CLI share this file).
Setup notes
The 2026 specifics.
Coming from Gemini CLI?
Google retired Gemini CLI for individual accounts on 2026-06-18; Antigravity is its successor and shares the ~/.gemini folder. The setup command writes ~/.gemini/config/mcp_config.json, which the Antigravity IDE and CLI both read. On a Workspace or enterprise Gemini CLI, `npx -y summer-engine@latest setup gemini --yes` still works.
Why this matters
Antigravity writes with your subscription. Summer Engine shows the game.
A chat agent alone can write files. With MCP, Antigravity gets tools for the running game engine, so it can inspect the project, run commands, and make changes that become playable inside Summer.