Teaching a machine to play Slay the Spire like a top streamer.
Slay the Spire is a deckbuilding roguelike with enormous branching: hundreds of cards and relics, random draws, hidden enemy intents, and a 50+ floor run where one bad fight ends everything. Spire Mind is a from-scratch AI that plays Ascension 20 Ironclad — the hardest difficulty — aiming to win as reliably as a skilled human. Below is the architecture at a glance, and the live runs page shows every decision it makes, as it makes them.
This is a research system in active training, not a finished bot. It has no verified A20 win yet. The ~90% figure is the goal — roughly a skilled Twitch streamer — and every training cycle chips away at the gap. Current, real numbers live on the live runs page — watch it play, wins and deaths alike.
Get your runs reviewed
Upload a run and the A20 bot reviews every decision: which card it would have drafted and why, how much HP each fight should have cost, and — for any fight — a step-through replay of the bot playing your exact spot. Join the waitlist and be first in when it opens.
Two brains, one run
A run splits cleanly into two decision problems, and the AI uses a dedicated model for each. They talk to each other: the map brain asks the combat brain "how much will this fight hurt?"
The Combat Brain
Inside a fight, every turn: which cards to play, in what order, on which target. It sees the literal battle state as a set of typed tokens and runs a Monte-Carlo tree search guided by a transformer that predicts the fight's outcome.
- Input tokenized battle state
- Model entity-token transformer
- Decision MCTS + CVaR risk selection
The Out-of-Combat Brain
Between fights: which path to take on the map, which cards to add or remove, what to buy, how to resolve events. It scores whole run states with a win-probability net that reasons over your owned set of cards and relics.
- Input deck + relics + run context
- Model owned-set attention net
- Decision path planner over win-prob