Battledrones, Simon Willison’s browser-based real-time strategy game, now has a Battledrones four player map. Version 14, released on 24 October 2026, adds “Compass Rose”, the first map that takes more than two players. Every earlier map was strictly head-to-head.
The interesting part is how it got built: one short prompt, and Claude Opus 5.5 did the map and the networking changes.
Key takeaways
- Battledrones v14 (24 October 2026) adds Compass Rose, a map for up to four players.
- The map has four-way rotational symmetry, so no corner gets a built-in advantage.
- Any slot a human does not fill is taken by an AI player.
- It runs on the existing WebSocket multiplayer mode, not the audio-based one.
- Purple and green robot teams join the existing blue and red.
What is Battledrones?
Battledrones is a Command & Conquer style RTS (real-time strategy game) that runs in a browser on phones and desktops. Willison introduced it on 20 October 2026 as a vibe-coded project, meaning he steered coding agents, mainly Claude Code, instead of writing the code by hand.
By his count it took 12 major iterations and 321 commits. It has fog of war, six maps across five biomes, a random map generator, Skirmish and Last Stand modes, and six AI personalities. AI Weekly also covered the launch.
What does the Compass Rose map add?
According to Willison’s release post, the prompt was short: add a map for a four player battle, with four-way rotational symmetry and up to four AI players. It had to work with the WebSocket, non-audio multiplayer mode, so up to four humans can join, with AI filling spare slots.
Claude Opus 5.5 produced a map called Compass Rose, set in the cold and ice biome and shaped like a rose. It also changed the WebSocket network code to handle more than two players. The post does not detail those networking changes, so treat the specifics as unconfirmed until you read the code.
Think of rotational symmetry like a pizza cut into four identical slices. Turn the board a quarter turn and it looks the same, so nobody starts with the better spot.
How do four players join a match?
Online mode uses share links or QR codes, as the two-player version does. Per Willison’s earlier post, it runs on a stateless WebSocket relay written with Python’s asyncio and deployed on a Fly.io shared-cpu-1x instance that scales to zero. He estimates it should cost no more than about $2.19 a month, even if it ran around the clock.
A relay like this just passes messages between players. That is why adding seats is mostly a matter of routing more connections, which fits the small prompt Willison used.
How does this differ from the older maps?
| Feature | Earlier maps | Compass Rose (v14) |
|---|---|---|
| Players | Two | Up to four |
| AI fill-in | Opponent only | Any spare slot |
| Team colours | Blue and red | Plus purple and green |
| Multiplayer mode | Audio or WebSocket | WebSocket |
The audio mode, where two devices in microphone range swap sound-encoded messages, stays two-player. Four players over sound would be a stretch, so the online relay does the work.
What else shipped in v14?
The updated model browser lets you preview the new purple and green robot designs. Willison also posted a replay of a four-way AI battle using the “Goliath Armada” mutator, where each side starts with four giant Goliath mech units. Mutators are rule tweaks that change how a match plays out.
Why does the way it was built matter?
Willison says he has reviewed almost none of the code, and he calls games “super low stakes”, which is part of why he is comfortable with that. He also notes that Math.sin and Math.cos gave slightly different results across browsers and broke replay sync, so Claude wrote custom versions.
My opinion: this is a good example of agent-assisted coding working best on bounded, forgiving projects. If you want the cautionary side, see our pieces on vibe coding and skill and on EVEngine, where Codex built a platformer.
What happens next
Willison has not announced a roadmap. Given 14 versions in a few months, more maps and modes are likely, but that is a guess. The game and its v14 release notes are public, so watch the releases page for what comes after.
FAQ
How many players does Compass Rose support?
Up to four. Any slot without a human is filled by an AI player.
Does the four player map work with audio multiplayer?
No. It was built for the WebSocket online mode, which uses share links or QR codes.
Who built it?
Simon Willison directed the work, and Claude Opus 5.5 wrote the new map and the networking changes.
Next step: open Battledrones v14, send a room link to three friends and see how the four-way symmetry plays.
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