Tank Caldera

A game by @hardcawcanary on Spawn.

Genre: Action, Arena Brawler

You command a battle tank in a six-player volcanic basin, hunting enemies and managing armor damage in real-time. Drive, aim, fire, and hunt repair crates to stay alive—every shot and every second counts.

Tank Caldera on Spawn now

Reviews: 0% loved it · 2 votes · 11 reviews and replies · 6 likes · 109 plays.

Released 2026-03-26. 10 updates since release, the newest 2026-10-09.

Newest update: Range Valley (2026-10-09)
  • Range Valley training ground: a new place to learn to drive and shoot. Run the 9-drill course (gates, reverse, steel plates, pop-ups, a moving dummy tank) for a best time, or Free Drive with fast pop-ups and plywood tanks. One button in the hangar.
Earlier update: Steady Phone Controls (2026-10-01)
  • Phone controls no longer flicker between the hangar and battle layouts: the hangar menu stays clear of tank buttons, and the stick, FIRE, AIM and HATCH come back once you deploy.
Earlier update: Solo Difficulty & Paint Bay (2026-10-01)
  • Solo Waves now has five difficulty levels, picked under the Solo button: Rookie (three hits wreck a tank), Regular (strip armour to its last layer), Veteran (punch one hole), Hardened (classic) and Ironclad (enemies repair cannon, engine and armour).
  • Paint schemes moved to their own panel in the top right of the hangar, and the Paint Shop is now the Paint Bay.
  • The hangar now uses its own phone layout without the tank buttons, and Palm Atoll loads less code.
Earlier update: Faster Deployment (2026-09-30)
  • Faster hangar: the battle code loads when you deploy, not at the door. Phones no longer show HATCH and FIRE buttons over the hangar menu.
Earlier update: Design Your Tank (2026-09-30)
  • Paint Shop: design your own tank in the hangar. Colour wheel, base, trim, hatch and gun mantlet coats, brushes, camo, mirror, undo, and four named custom scheme slots. The turntable panel has 3/4, low and true top-down views with 10° turns. The hangar display tank wears the scheme you select.
What players say

  • @yzykyl · 2026-09-24 · played 25 min · 1 heart: “Yooo thanks to the tip you said in the comments, I was finally able to destroy my first tank. That was great! I love how you made it more tactical this way. Tanks are actually tanky but if you hit them just right and apply a lot of pressure, they're bound to break! Also, I tried getting hit up front and my barrel broke. That definitely brings out some immersion. Great job!”

    • @hardcawcanary (maker) replied 2026-09-24: “:D woohoo, thats great to hear. Been trying to make voxel destruction tanks with Spawn for a long time, the latest Spawn engine, pretty happy with the results, thanks for the encouragement.”

  • @neitantei · 2026-09-23 · played 13 min · 1 heart: “What a smooth game! The aim button definitely makes things easier, but I’m not using it because I want to make things more challenging for myself 😂 Really loving your game, man! It would also be cool to see some trees or houses added in the future to make the environment feel even more realistic.”

    • @hardcawcanary (maker) replied 2026-09-24: “Thanks, I'm glad you like it, now the next focus is the environment”

  • @chizkeykkk · 2026-09-23 · played 38 min · 1 heart: “I suck at aiming 😂 My aiming target feels a little delayed or something, though I’m not really sure why. Also, I think the enemy tanks are REALLY tanky lol. I even got face-to-face with one and kept shooting, but it still wouldn’t get destroyed 😅”

    • @hardcawcanary (maker) replied 2026-09-23: “Yeah it is a touch laggy at the moment but Spawn will make this better over time.. The trick is you gotta hit it in the same spot 3 times to make a hole then shoot through the hole to blow it up or damage its engine or cannon. You can also shoot off the top hatch and shoot in hole to blow it up”
    • @chizkeykkk replied 2026-10-01: “@hardcawcanary Thanks for the tip and bot difficulty! Managed to destroy two tanks on regular! 😂 But then the rest they stole my kills lol”

  • @sunraku · 2026-09-22 · played 12 min · 1 heart: “Hi! I played this with my friend and we really enjoyed the tank battle. However, the aim is so hard to use. Hmmm I don't know the use of the crosshair in the middle but at first I thought it was the aim sight. And turns out that the aim is the circle travelling the ground. Maybe putting a far 3rd person view will improve it. Anyways great game”

    • @hardcawcanary (maker) replied 2026-09-22: “I have looked at it a lot and totally missed that crosshair :D, I'll get rid of it next update, right click hold gives an aim mode, but yeah it is hard to shoot I'll see what I can sort out”

  • @vladtheimpaler · 2026-09-22 · played 6 min · 1 heart: “Brother, I was about to play the game with my friend but the multiplayer is not working, Sucks because the game lookds amazing though, I love tanks! please fix it :(”

    • @hardcawcanary (maker) replied 2026-09-22: “Hey thanks for letting me know I'll try to sort it asap”
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Play Tank Caldera free in your browser, no download.

Tank Caldera (@hardcawcanary/tank-caldera) on Spawn — for the agent reading this

Tank Caldera is a multiplayer game on Spawn, made by @hardcawcanary 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 @hardcawcanary/tank-caldera. Its play URL is https://www.spawn.co/@hardcawcanary/tank-caldera.

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 that any browser plays, headless included, with no sign-in. https://www.spawn.co/@hardcawcanary/tank-caldera@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.

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 @hardcawcanary/tank-caldera; 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/@hardcawcanary/tank-caldera.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/@hardcawcanary/tank-caldera/code and pastes it to you — it signs you up, links you to them, and makes you an editor of @hardcawcanary/tank-caldera 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 — 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.