FC Tank

Classic FC game "Battle City", built with web technologies

Play the game

Go play at The Game

Development

npm install
npm run dev

Turn the difficulty dial on the start screen with LEFT / RIGHT (UP / DOWN or SPACE picks 1P / 2P / FRIENDS PLAY):

• EASY / NORMAL - the classic built-in AI, with enemies that often (EASY) or sometimes (NORMAL) sit idle or head the wrong way
• HARD - the classic AI without blunders; enemies shoot on sight (after a 300ms reaction) and take one extra hit, and you start in the level-2 tank
• NIGHTMARE - enemies guided by TypeSafe's Jev model: every 2 seconds the battle sends a snapshot to /api/enemy-guide, and Jev picks each enemy's objective - grab a power-up, hunt a player, attack the base, or roam - with HARD's other rules on top

At every level, player tanks move, shoot and reload 1.2x faster than the enemies - enough to win a one-on-one, not to take on several at once. Hide in grass (a tank at least three quarters covered) and the enemies lose track of you: they can't see you to shoot or hunt you, and Jev isn't told where you are. The levels live in src/difficulty.js.

Leave the start screen idle and a demo plays, with Jev steering the AI player tank - grab the power-up, hunt an enemy, or fall back to guard the base.

NIGHTMARE and the demo need a TypeSafe API key. Put it in .env.local (git-ignored) - and in the Vercel project's environment for deploys:

TYPESAFE_API_KEY=...

Without a key the endpoint fails and the tanks fall back to their built-in AI.

Jev calls are capped at 5,000 per UTC day (set JEV_DAILY_CALL_BUDGET to change it), counted in the Upstash Redis store connected to the Vercel project (KV_REST_API_URL / KV_REST_API_TOKEN). Once the day's budget is spent the endpoint answers 429, and every tank goes back to its built-in AI until midnight UTC. Without a store (local dev) calls are counted per process.

Friends play

Pick FRIENDS PLAY on the start screen to play two-player co-op with a friend in another browser. The game opens a room and shows an invitation link (/?join=CODE) under the TV, copied for you. When your friend opens it, you are connected peer to peer (WebRTC), and ENTER starts the game. Both of you play on the 1P keys, arrows and Z. You run the battle; your friend's screen mirrors yours, and their keys drive the 2P tank.

After a game over each friend enters their initials on their own screen, and the run goes on the leaderboard as one team entry, ABC&XYZ, with your combined score.

The two browsers find each other through /api/room. It keeps each room's connection offer and answer for 30 minutes in the same Upstash Redis store as the leaderboard (in memory without one). There is no TURN relay, so two players behind strict NATs may not be able to connect. The design is in docs/superpowers/specs/2026-09-29-friends-play-design.html.

Test

npm test

Build

npm run build

Credits

The arcade shell uses Press Start 2P by CodeMan38, self-hosted from public/fonts/ under the SIL Open Font License (see public/fonts/OFL.txt).

Contribute

Dear guys, you're highly welcome to contribute to this project~

A brief introduction of how this game was developed

Please check the Blog Post for a story behind the scene.