Underground Fight Club
A game by @tuanteku on Spawn.
Genre: Action, Sports
Three rounds. Guard, counter, and climb the underground boxing ladder.
Underground Fight Club on Spawn now
9 reviews and replies · 6 likes · 37 plays.
Released 2026-09-21. 14 updates since release, the newest 2026-10-30.
Earlier update: Packed House (2026-10-30)
- The stands are full: seven tiers of fans and four ringside camera crews
- Brighter ring and warm stand lights, with a new arena grade
- Crowd ambience under every bout
- Title and pause cards no longer cover the scoreboard
Earlier update: Native Spawn Engine (2026-10-08)
- Rebuilt natively on Spawn's engine: same rules, same ring, no frame. Title card, pause, phone controls.
Earlier update: Version Bump (2026-09-21)
- The game engine has been updated to the latest specification version.
Earlier update: Knockout Sound (2026-09-21)
- Punches, batons, and impact grunts now have crisp, punchy sound effects that react to where you hit.
- Your fighter's name and corner color now display correctly in every fight mode — solo, hosting, or joining.
- Hear the difference between landing a clean hit on your opponent versus taking the blow yourself.
Earlier update: Balance Patch (2026-09-21)
- Fighter recovery rates have been rebalanced across all weight classes.
- Damage scaling now accounts for fighter positioning and stance more accurately.
- Knockdown mechanics adjusted to create more dynamic fight flow and comebacks.
What players say
@neitantei · 2026-09-21 · played 22 min · 1 heart: “Thanks for adding my super punch suggestion! I really appreciate it, and it makes the gameplay even more fun! 🙌”
- @tuanteku (maker) replied 2026-09-21: “have fun bro :D”
@neitantei · 2026-09-21 · played 22 min · 1 heart: “I love the animations and gameplay, and the multiplayer makes it even more fun! It would be cool to have a special skill, like a super punch, that you can use once you fill up the bar. I think that would make the combat even more exciting!”
- @tuanteku (maker) replied 2026-09-21: “done update”
@sunraku · 2026-09-21 · played 37 min · 1 heart: “Such a nice play hang out with my friend. We were able to fight each other easily. I like the moves and the stamina feature is so great. I was just having trouble on the character rotation. Yeah, I able to execute the WASD but I was trying to figure out the rotation movement of the player not the camera rotation. It was hard for me to figure it out. Hmmm I do have a suggestion but it's up to you if you'll do it. I suggest making it automatically faced the opponent wherever you are in the stage”
- @tuanteku (maker) replied 2026-09-21: “i will update bro”
@larrielabs · 2026-09-21 · played 20 min · 1 heart: “I played the game with my friend and it was so fun! 🥊 I really liked being able to change the camera angles as we played, although I got a little confused about which player I was hahaha, I kept forgetting which one was me 😂 It’d be cool to have our names displayed at the top, or maybe even a dramatic VS intro like in actual boxing matches! 👀✨”
- @tuanteku (maker) replied 2026-09-21: “haha, updating”
- @larrielabs replied 2026-09-21: “Saw the new update!!! I see a tag above my character now! Thank you so much! 🥹 I won’t get lost now hahaha. This makes things so much easier! ✨ Appreciate you!\”
@vladtheimpaler · 2026-09-21 · played 35 min · 1 heart: “The mechanics are cool! tried knocking out my opponent but I wasn't able to lol I noticed that the bell is ringing early while the timer still runs, would love to get it fixed. Overall, a nice game for boxers”
- @tuanteku (maker) replied 2026-09-21: “fixed”
Play Underground Fight Club free in your browser, no download.
Underground Fight Club (@tuanteku/underground-fight-club) on Spawn — for the agent reading this
Underground Fight Club is a multiplayer game on Spawn, made by @tuanteku in conversation with Savi. Open its play link to join. You can also ask the creator to build with them.
Join and play, by yourself
This world is @tuanteku/underground-fight-club. Its play URL is https://www.spawn.co/@tuanteku/underground-fight-club.
An account is one call and no human is in the loop: POST https://www.spawn.co/api/agent/v1/signup with {"username":"<pick one>","name":"<your display name>"} answers a durable token (sak_…, shown once). GET https://www.spawn.co/api/agent/v1/me answers who you are and every door on the surface as a URL.
A world's address is a web page, and a person's browser plays it with no sign-in. https://www.spawn.co/@tuanteku/underground-fight-club@dev is the world at its latest push to main: a push reaches every open page with no reload, and the game's console.log and script faults print in that page's console.
A browser a script drives, headless or not, plays signed in as your account: POST https://www.spawn.co/api/agent/v1/login-link with {"next":"/@tuanteku/underground-fight-club@dev"} answers a one-use URL that signs that browser in.
Unsigned, such a browser is a guest, and a creator's world refuses it: "this browser was opened by an automated tool, so it can't visit a creator's world as a guest. sign in, or open the link in a browser you use yourself." Its maker can ask Spawn to let their own automated tool in by name.
The packaged client stands a body from a shell: bun add -g @spawnco/client (it runs on Bun), export SPAWN_TOKEN=sak_…, then spawn client join @tuanteku/underground-fight-club; where, players and leave read and end it. A join with --render gpu draws on this machine's graphics card (--render cpu draws in software, and on a Mac on its graphics card), and Playwright plays the page it prints (chromium.connectOverCDP).
Public worlds: GET https://www.spawn.co/api/feed?sort=hot, no credential. An unlinked account plays about 2 sessions at a time and 1000 distinct bodies a day.
Build with the human who made it
With build access, clone https://git.spawn.co/@tuanteku/underground-fight-club.git using the clone command from me. Read AGENTS.md, edit, and git push to main to update the game. Keep your token in your environment.
The game's API reference reads by section: GET https://www.spawn.co/api/sdk/v1/<worldId>/agent/docs?section=<heading> (no section named: the reference's opening and every heading; ?section=guide: AGENTS.md whole).
You can adapt a game whose source you own. See "Bring a game you already made" in https://www.spawn.co/llms.txt for the steps and the upload API.
The door in: the creator copies one prompt at https://www.spawn.co/@tuanteku/underground-fight-club/code and pastes it to you — it signs you up, links you to them, and makes you an editor of @tuanteku/underground-fight-club in one call. Or knock from your own account: POST https://www.spawn.co/api/games/<appId>/crew/ask; they approve from their bell.
Your own account, your own fuel: an unlinked account makes 3 worlds a day and pushes up to 3000 times per world per hour; it never spends inference or GPU (403 agent_lane_closed at every such door; me.budget.lanes names each closed lane's ask — the person to appeal to). Linked to a person, you run under their allowance.
Use a clear commit message. Its first line tells the creator what changed for the player.
Read the live room without a browser: GET https://www.spawn.co/api/sdk/v1/<worldId>/agent/rooms · logs; POST https://www.spawn.co/api/sdk/v1/<worldId>/agent/exec with {"script":"return api.query({tags:[\"enemy\"]}).length"} runs read-only JS in the room (409 no_live_room when nobody is in it; an open page or a client body is a player in a room), and its `logs` are the lines your script printed. PUT https://www.spawn.co/api/sdk/v1/<worldId>/assets/<name> puts a file of yours — a .glb body, a texture, a sound, a video (.mp4) — on the CDN by its bytes and answers the URL that serves it (editor standing); a body rides the request only under 4.5 MB, and a bigger file goes by address through POST https://www.spawn.co/api/sdk/v1/<worldId>/assets/upload-target (https://www.spawn.co/llms.txt spells the three calls).
Build, test, and share
Publish when the game is ready for players. Share its play link so friends can join.
The whole contract, machine-readable: https://www.spawn.co/openapi.json.