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Summer’s AI-agent layer is MIT open source. The Summer Engine desktop app is free to download and use, but its source code is not public right now. This page is also the single canonical status source for Summer Games platform capabilities: reference pages describe contracts, while this page says whether the supporting production path is live.

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What is open today?

The public repo is the agent layer:
  • CLI
  • MCP server
  • Agent skills
  • Hooks
  • Plugin manifests
Repo: github.com/SummerEngine/summer The hosted MCP server at https://mcp.summerengine.com/mcp is run by Summer and is not in this repo.

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What is free?

The Summer Engine desktop app is free to download and use. Local MCP workflows are free too, including workflows where you bring your existing Claude Code, Cursor, Codex, Gemini, Devin Desktop, or other agent subscription.

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What is paid?

Live hosted Summer services are paid because they run cloud infrastructure and model calls:
  • Hosted Summer AI
  • Asset generation
  • Cloud storage
  • Orchestration
  • Managed multiplayer
Managed multiplayer is live for published Summer 0.7 games; see the table below.

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Platform capability status

Status words are deliberate:
  • Live means the production path is deployed and documented.
  • Scaffold means a contract, adapter, or tested local surface exists without a complete production path.
  • Planned means creators and agents must not promise the capability.
See Make a multiplayer game on Summer Games to build a Summer game and Publish your game to release it on summer.games.

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Is the engine app open source?

No. The desktop app is free proprietary software right now. If Summer publishes engine source later under a no-competing-engine license, the honest term would be source-available, not open source. For the public canonical page, see summerengine.com/source-status.