RELIC - The Last Light
A short 3D action prototype in a ruined sky temple, made in one day by Codex as a test of building a Unity game from natural-language instructions.
Official site allegromoltov.itch.io, verified Nov 3, 2026. The developer's own itch.io page, linked from the developer's Qiita post.
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- Play free — itch.ioitch.ioReleased · Listed as “Prototype” on itch.io; HTML5Free
Plays in the browser on itch.io. No download.
Browser (no download) · Official link verified Nov 3, 2026.
About RELIC - The Last Light
A short free 3D action game that runs in the browser. In a ruin in the sky that has lost its light, you wake three altars, fighting enemies at each and choosing an upgrade, before facing the guardian, which appears in the centre of the area you have been exploring. Exploration, combat, upgrades and the boss fight form one continuous run. It is played with keyboard and mouse (WASD or arrow keys to move, left click to shoot, a held auto-aim key, a dash, and E to activate altars and gates); there are no smartphone controls, and the text is in Japanese. The developer, あれぐろもると, made it on 20 Sep 2026 as a test of making a game from natural-language instructions with Codex using the GPT-6 Astra model, after a friend asked whether someone with no programming skills could do it. The itch.io page says the C# code, the scenery built from basic shapes, the synthesized sounds and the on-screen text are AI output; the developer play-tested it and calls it a rough prototype.
How it was built
Partially verifiedThe itch.io page says the game was made on 20 Sep 2026 with Codex using GPT-6 Astra (reasoning set to high) as a test of making a game from natural-language instructions, and that the C# code, the scenery built from shapes, the synthesized sounds and the on-screen text are generative-AI output. The Qiita post adds that, with the developer having specified Unity 6000.6.2f1 and a Unity MCP connection, Astra chose the rest of the setup (URP, connected through CoplayDev/unity-mcp v10.0.0), wrote the game logic, terrain, shape-based models and generated sound in C#, play-tested it itself through computer use, and later made the Web version, building, uploading and checking it in the browser; the developer only installed Unity's Web Build Support and logged in to itch.io. The developer concludes that a playable short 3D game could be made without a human writing the game's code.
- DeveloperQiita post: AI agent Codex / GPT-6 Astra (reasoning high); Astra built, tested and uploaded the game; the developer reviewed and play-tested it. — Qiita (@AllegroMoltoV)
A one-day experiment: the developer gave Codex a written brief (show an example of a game that can be made from instructions alone, then ask the developer to play it and give feedback), specifying Unity 6000.6.2f1 with a Unity MCP connection, and let the agent choose the rest of the setup and build it. Codex wrote everything in Unity C#, used no purchased assets, built a Windows executable and, on a follow-up request, a WebAssembly build for itch.io, and played the game itself through computer use. On-screen buttons were added during development because key input from computer use did not register reliably. The developer played the result and noted remaining rough spots, such as altars responding to the E key but not to clicks. The developer says no comparison with the Sol model was made.
- Engine / framework
- Unity 6000.6.2f1 (URP)
- Languages
- C#
- Team size
- Not disclosed
- Initial build time
- About 40 minutes from initial research and setup to the Windows build launchingDeveloper ReportedQiita (@AllegroMoltoV)
- Development time
- Not disclosed
- Development cost
- Not disclosed
- AI-written code
- Not disclosed
Verification notes: AI use from the developer's itch.io page (“CodexのGPT-6 Astra（推論設定high）で制作しました”; C# code, shape-based scenery, synthesized sound and on-screen text are AI output) and the developer's Qiita post of 20 Sep 2026 (07:37 UTC), which agree; the itch.io AI disclosure ticks Code, Graphics, Sounds and Text. The Qiita post concludes that the game was made without a human writing its code, but gives no share, so none is recorded. Release date is the day the itch.io page says the game was made; the page shows no separate publication date. The Windows executable mentioned in the post is not offered on itch.io, which lists HTML5 only. Gameplay and controls from the itch.io page; the boss appearing in the centre of the area from the post. The game file's language is Japanese (lang=ja). Whether anyone else was involved is not stated, so team size is not recorded. No ratings are shown on the page. The developer's location is not stated.
Development history
Made with Codex and published on itch.io as a prototype; the developer's Qiita write-up appears the same day.
Game performance
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itch.io
Free in the browser. The page says to play with keyboard and mouse; smartphone controls are not supported.
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Not publicly available: itch.io rating, Gross revenue.
Sales & revenue (all platforms)
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Reviews & rankings
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Sources
| Source | Type | Published | Accessed |
|---|---|---|---|
| RELIC - The Last Light by あれぐろもると itch.io · Japanese | Store page | Not confirmed | Nov 3, 2026 |
| Codex の Astra に Unity ゲームを作ってもらった Qiita (@AllegroMoltoV) · Japanese | Devlog | Sep 20, 2026 | Nov 3, 2026 |
| Official game page (language check) あれぐろもると | Official site | Not confirmed | Nov 3, 2026 |
