Games / AI games / Made with Fable 5

A game made with Claude Fable 5

Plops — our free 2v2 card MOBA — has been in development across several generations of Claude models. When Anthropic shipped Fable 5, we pointed it at a live game with paying players and real uptime stakes. These are the field notes.

What a Fable 5 session looks like

The unit of work changed. With earlier models the workflow was "describe a function, review a function." With Fable 5 the workflow is closer to handing a colleague a problem: "payments need to go live — Stripe checkout, webhook fulfillment, refunds path, and the store UI has to say when keys are missing instead of showing a broken button." The model reads the codebase, finds the conventions, builds the whole slice, runs the typechecker, and writes the changelog entry our deploy tool requires. The human contribution concentrates into two moments: the framing at the start, and the judgment at the end.

Things it did that earlier models didn't

• Holding the whole system. A card MOBA is one simulation with many faces: server sim, client prediction, deck builder, matchmaking, the shop. Fable 5 keeps the invariants — "the server is the referee," "no image assets, everything is canvas" — without being reminded per file.
• Disagreeing usefully. Asked for a feature that would have quietly broken ranked integrity, it pushed back with the failure case instead of complying. That's new, and it's the difference between a tool and a collaborator.
• Boring things, perfectly. Byte-range audio streaming for mobile Safari, idempotent webhook fulfillment, reconnect-into-running-match. The unglamorous 40% of a live game is where model quality actually shows.

What still belongs to humans

Taste. Whether a three-minute match feels tight or rushed; whether the Junk Empire reads as funny or mean; whether a hero's dash is juicy. The model executes feel adjustments brilliantly but doesn't own the opinion. Somebody still has to play the build on a phone in bed and say "again." That division of labor — model does volume, human does taste — is the entire thesis of how we make games.

Try what it built

The game is free and takes ten seconds to enter: plops.io. The tools and workflows behind sessions like these get shared on Plops Forge — tip-based, source visible, read before you run. For the earlier chapters of this story, see building with Claude Opus, and the devlog for what ships next.