Mars Rally Championship
Free · play online in your browser, no download
Free 3D rally racing on Mars: an electric rover, a third of Earth's gravity, daily seeded stages and online rooms for up to eight pilots.
Official site marsrallychampionship.com, verified Nov 3, 2026. Entry URL submitted under the X handle dontgetrekt in the official Vibe Jam 2026 games data; the site's own developer write-up is signed by @dontgetrekt and its structured data links x.com/dontgetrekt and x.com/marsrallychamp.
Where to play
Every platform this game is on. Links are checked against official sources; we never host or mirror games.
- Play free — official siteBrowserReleasedFree
Runs in a desktop or mobile browser. No download.
Browser (no download) · Mobile · Official link verified Nov 3, 2026.
About Mars Rally Championship
A free 3D rally game in the browser, set on Mars. You drive an electric rover over dunes, basins and ridgelines at Martian gravity (the site gives 3.71 m/s², about a third of Earth's), watching power draw, battery charge and regeneration on the HUD; each stage can be driven forward, reversed or in a full dust storm with crosswinds that drains the battery faster, and a voice co-driver calls the route. On 5 Nov 2026 the menu listed four stages, with more “under survey”. There is a Mars Cup championship, practice runs against medal times, a new seeded daily challenge with streaks and supply crates, a tutorial, free roam, online races for up to eight pilots in public or private rooms, ghost replays and a leaderboard on which every time is re-simulated from the run's recorded inputs before it is posted; paints, rims and calipers for the rover are earned by driving, with nothing to buy. It plays on desktop with keyboard or gamepad and on phones with touch controls, with no download or sign-up. The game was started on 26 April 2026 for the Cursor Vibe Jam 2026, whose rules required at least 90% of each game's code to be written by AI; the official submission lists Claude Code as the tool, and it finished 229th of 945 entries. The developer, @dontgetrekt, kept working on it afterwards and wrote on the game's site that AI coding agents (commit authors “Claude” and “Cursor Agent”) did most of the typing, while the decisions stayed with the developer.
How it was built
Partially verifiedIn the official Vibe Jam 2026 submission the entrant lists Claude Code as the tool and answers Yes to the AI-written field. In a write-up on the game's site (6 Sep 2026, updated 11 Oct 2026) the developer says the game started from a game-jam starter pack and that most of the typing was done by AI coding agents working on branches: 83 of 291 commits carry an agent as the author and 54 merged pull requests came off agent branches. A diagram of the first 290 commits (26 April to 30 August 2026) counts 207 by mlsmi, 55 by “Claude” and 28 by “Cursor Agent”. The developer calls commit authorship “a crude proxy” and writes that by characters typed the agents wrote “the large majority of this repo”, while by decisions they wrote almost none of it. The write-up names the commit author “Claude” without naming the product; Claude Code is the entrant's answer in the jam data.
- DeveloperDeveloper write-up: “most of the typing was done by AI coding agents working on branches” and “If you measured characters typed, the agents wrote the large majority of this repo.” — Mars Rally Championship (by @dontgetrekt)
- OfficialJam rule 3: at least 90% of the code has to be written by AI. — Vibe Jam (Pieter Levels)
The same write-up's commit diagram counts 28 commits by “Cursor Agent”, the second agent identity in the repository; the developer says they moved between agents over the summer and did not run a controlled comparison.
Started on 26 April 2026 from the Vibe Jam Starter Pack. Per the developer's write-up, the game is now a no-build browser game of 44 vanilla ES modules with a self-hosted copy of Three.js loaded through an import map, wrapped in a Next.js App Router site; about 38,000 lines over 291 commits by 6 September 2026 (19 weeks, mostly evenings). The developer describes machine-checkable guardrails as the main work: a zero-dependency test script with 25 structural checks (including one that fails when a module is never imported and a guard that fails when the site's copy of the game's constants drifts), lint rules, and 52 Playwright tests across 11 spec files that boot and drive the real game. The physics runs at a fixed 60 Hz step with a per-wheel tire model, so runs replay bit for bit and the server re-simulates each leaderboard run. Stage routes are hand-placed in a dev-only level editor, which the developer names as the bottleneck no agent could remove.
- Engine / framework
- Three.js
- Languages
- JavaScript
- Team size
- Not disclosed
- Development time
- Not disclosed
- Development cost
- Not disclosed
- AI-written code
- Not disclosed
“If you measured characters typed, the agents wrote the large majority of this repo. If you measured decisions, they wrote almost none of it.”Verification notes: Tool (Claude Code), engine (ThreeJS), genre (Racing) and the multiplayer (No), mobile (Yes) and portal (No) flags from the entrant's answers in the official Vibe Jam 2026 games data (submitted 1 May 2026, 13:18 UTC; final rank 229 of 945 entries, no award), re-read on 5 Nov 2026; rule 3 on the jam page requires at least 90% AI-written code. The online races for up to eight pilots, accounts and the daily challenge are on the site as of 5 Nov 2026 and were not part of the submission's answers; the game has been updated since the jam. Commit counts, line counts, tests and the agent names come from the developer's write-up (published 6 Sep 2026, updated 11 Oct 2026); its text gives 291 commits (208 by the developer, 83 by agents) to 6 Sep, and its diagram gives 290 commits (207 by mlsmi, 55 by Claude, 28 by Cursor Agent) to 30 Aug, so the two counts have different cut-off dates. No AI code share is recorded: the developer calls commit share a crude proxy and gives no percentage for code written. Developer: the write-up is signed @dontgetrekt (the X handle in the jam entry), the git author name shown is mlsmi, and the game also has an X account @marsrallychamp; no real name, location or team size is given. Gravity, stage list, modes and garage counts from the site's home page on 5 Nov 2026; the game was not played. The site's scripts were checked for calls to AI services and none were found. The jam page's widget counter showed 283 plays for marsrallychampionship.com on 5 Nov 2026 (observed; plays are sessions, not players or downloads, so not recorded as a metric). The release date is not stated; the jam submission is dated 1 May 2026.
Development history
First commit: the Vibe Jam Starter Pack, per the developer's write-up.
Entered in the Cursor Vibe Jam 2026 (submission date in the official games data, 13:18 UTC); the jam required at least 90% AI-written code. Final rank 229 of 945 entries, no award.
Developer publishes “How I Built a 3D Mars Rally Game With AI Coding Agents” on the game's site (updated 11 Oct 2026).
Game performance
Each figure measures something different — concurrent players, owners, downloads and sales are never interchangeable and are never added together. Labels show where each number comes from.
Browser (official site)
Free in the browser with no download or sign-up; an optional account (sign-in) exists. The site says there is nothing to buy.
No public metrics recorded for this listing.
Not publicly available: Concurrent players (site), Monthly revenue, Gross revenue.
Sales & revenue (all platforms)
Browser game — there are no downloads to count.
Reviews & rankings
Not yet reviewed by our editors.
Not currently ranked.
Sources
| Source | Type | Published | Accessed |
|---|---|---|---|
| Cursor Vibe Jam 2026 — rules, prizes and game stats Vibe Jam (Pieter Levels) | Official site | Not confirmed | Nov 3, 2026 |
| Vibe Jam 2026 games data (entrant submissions, final rank, awards) Vibe Jam | Official site | Not confirmed | Nov 3, 2026 |
| Mars Rally Championship — Free 3D Rally Racing on Mars (official site) Mars Rally Championship | Official site | Not confirmed | Nov 3, 2026 |
| How I Built a 3D Mars Rally Game With AI Coding Agents Mars Rally Championship (by @dontgetrekt) | Devlog | Sep 6, 2026 | Nov 3, 2026 |
| Official game page (language check) Mars Rally Championship | Official site | Not confirmed | Nov 3, 2026 |
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