What is Jev plays Tetris?

A small web app where TypeSafe's Jev model plays Tetris by itself; the only control is Reset. Each new piece becomes candidates with computed board facts, one typed Choice call picks the placement, and the page animates the result.

How does Jev choose a placement?

Code lists every placement the piece can reach (rotate, shift, drop) and computes facts such as lines_cleared, new_holes, stack_height, bumpiness and piece_top_height. Those candidates go to Jev as a single typed Choice question — there is no hand-tuned scoring formula.

What do I need to run it?

Node.js 20+ and a TypeSafe API key. Run npm install, then TYPESAFE_API_KEY= npm start, and open http://localhost:3000; set PORT to use a different port.

Is my API key exposed to the browser?

No. The key stays on the local server; the browser only talks to /api/decide. The README notes each piece is one TypeSafe request.

What does the decision panel show?

Jev's top candidates and their probabilities, the confidence of the choice, the latency of the call, the cost of the call, and a running total of what the game has spent.

How much does a game cost?

Cost is computed from the input tokens the API reports at Jev's listed price of $0.042 per million input tokens — output tokens are free. If pricing changes, update USD_PER_INPUT_TOKEN in server.js; the README gives no total per-game estimate.

The game waits for Jev before moving each piece, so network latency never ends a game. Tests are node:test unit tests, and there are no accuracy benchmarks; the cost panel depends on the README's listed rate and the API's reported token counts.

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CommunityJev Demos & Experiments

Jev plays Tetris — pinebit

A small web app where TypeSafe's Jev plays Tetris by itself — the only control is Reset. Code enumerates every reachable placement and its board facts, and one typed Choice call picks the move with probabilities, latency and cost.

See highlights Open github.com

Stars: 1
Language: JavaScript
License: MIT
Reading time: 2 min
Published by: Community
Author: pinebit
Last verified: Oct 2026

pinebit/jev-tetris

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Tetris that plays itself: TypeSafe's Jev model picks every placement with one typed Choice call, with live probabilities, latency, and cost.

Forks: 0
Last pushed: Updated Sep 2026

Repo stats from the GitHub API, cached Oct 2026.

Tagscommunity catalog-import logicrw tetris game-ai

Works forJev for Realtime control Jev for Ranking

Used inJev for Gaming

Languages: JavaScript
Platforms: Browser
Capabilities: Open sourceRuns locallyRequires API key

Highlights

For each piece, code lists every reachable placement and computes lines_cleared, new_holes, stack_height, bumpiness and piece_top_height.
Those candidates go to Jev as a single typed Choice question; there is no hand-tuned scoring formula.
The decision panel shows top candidates, probabilities, confidence, latency and the call's cost, plus a running total.
Costs are computed at Jev's listed $0.042 per million input tokens; output tokens are free.
The game waits for Jev before moving each piece, so network latency never ends a game.

Quickstart

bash

npm install
TYPESAFE_API_KEY=<your key> npm start

Watch out

Copy reviewed against the full repo README on 2026-10-15. Cost figures come from the README's listed rate and the token counts the API reports, not from an independent bill; the repo states no accuracy benchmarks and prices may change, so the constant in server.js may need updating.

Questions about this entry

Short answers drawn from the linked project or page.

Other listings of this project

Forks and copies of this project in the directory. This entry is the canonical one.

Jev plays Tetris

A live Tetris board where each piece is one Jev Choice over the legal placements, with latency and cost shown as the pieces drop.

Jev Demos & ExperimentsPlayground#community#games#playground

Community

From the Jev guides

Original write-ups on what this entry is for.

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Sep 28, 2026

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