CommunityJev Demos & Experiments
MCJev
A public Minecraft Java server where a diffusion model called DJev scores every combat move in one pass. The lobby board tracks rounds against real players.
- Format
- Playground
- Published by
- Community
- Last verified
- Sep 2026
Works forJev for Realtime control
Used inJev for Gaming
Highlights
- Join at mc.alexzms.com on Java Edition 1.9 or newer. No port. The page says nobody is driving the bot.
- Each step is text: position, health, nearby blocks, and the held item. DJev scores every move in one forward pass.
- The page quotes about 24 ms median and close to 40 decisions a second on the fast engine.
- The lobby board, refreshed every minute: 348 rounds, 290 won by the bot (83%). One player went 0 for 32.
Watch out
The fighter is DJev, a diffusion model on the operator's engine, not a call to TypeSafe's Jev API. The win counts are the site's own board.
Questions about this entry
Short answers drawn from the linked project or page.
The site says nobody is controlling it. A bot client sees what a player sees and writes the fight down as text — your position, its health, nearby blocks, the held item — and DJev scores every possible move in a single forward pass on B200 GPUs. The top-scoring move becomes keystrokes, then it repeats.
The same model on stock vLLM measured about 60 ms per decision in the earlier real rounds, so the operator's own engine is roughly 2.5x faster. Both figures are client-observed medians over real rounds rather than a synthetic benchmark, and the run generated no tokens at all.
They are the lobby board, refreshed every minute: 348 rounds against real players, 290 won by the bot, and one player 0 for 32. Those are whoever joined, across several modes with different rulesets, and no control run against a scripted bot is published.
There is a Workshop that writes three small files in the browser — what your bot reads and what it can do — previews the choices on moments from real rounds, then deploys into the game. Scope matters, though: this is DJev, the operator's diffusion model on its own engine, not TypeSafe's Jev API.
Block UHC is 1v1 in a walled arena with a diamond sword, bow, arrows, lava and water buckets, and cobblestone. Sumo drops the weapons for one platform. 2v2 Teams uses /party invite to face two Jevs, and Sudden death doubles damage at 60 seconds before a lava-ringed final platform with no blocks.
Yes. Fall and you stay on as a ghost to watch the end, and every round closes with a recap showing hearts left, damage, hits, and arrow accuracy. The lobby board tracks the fastest Jev kills and most kills by Jev, and /top shows your own stats.
The page quotes about 24 ms per decision on the operator's engine, roughly 2.5x faster than the same model on stock vLLM at about 60 ms. For scale it lists a Minecraft server tick at 50 ms and a typical human reaction at about 250 ms.
Reactions & coverage
Posts, threads, and videos about this entry from around the web.
Hacker News: Show HN for public Minecraft PvP where a diffusion LM picks moves from structured state.
2 pointsShow HN: Minecraft PvP against DiffusionGemma-as-Jev, 24 ms per decisionRead the thread on Hacker NewsHacker News: Show HN: OpenDecision, a local decision model with a Doom demo.
dwa35926 pointsShow HN: OpenDecision – a 400M zero-shot model makes local decisions, plays DoomRead the thread on Hacker NewsLinkedIn: What multimodal decision models actually change, and what they do not.
LinkedInJevDirectory.org
Hacker News: Decision Index 0.2.1 scores open reproductions of Jev on a frozen suite.
jackbravo4 pointsDecision Index 0.2.1 – 70 open reproductions of TypeSafe Jev's Decision ModelRead the thread on Hacker NewsMore Jev resources like this
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