Hearts is a game where the lowest score wins and the boldest play is shooting the moon. A perilune is the point of a lunar orbit closest to the Moon - the lowest point, at the moon. One word, both ideas. That's the name of the AI you're playing against.
Perilune is a neural network trained to play Hearts as a match - games to 100, lowest total wins - rather than deal by deal. It learned by playing millions of games against itself, guided by search and a learned sense of its chances of winning the match. This site is its public table: one human seat (or up to four, at a hosted table) against the current strongest network.
Matches are recorded anonymously to improve the AI: the cards played, timing, and outcomes of each deal, tied to a random identifier stored in your browser. No accounts, no emails, no personal information. Human games are especially valuable because people find weaknesses self-play never does.
Perilune is an ongoing experiment in training a card-game AI end to end - engine, search, training loops, and measurement discipline. The pipeline and the gates that decide what ships are explained on How it's built, and the whole project is open source: code, released model weights, and the full measurement record live at github.com/JAkoliver/hearts_simulator. If you'd like to help keep the table running, see Support: supporters get a moon badge by their name and an exclusive emote pack.
Emote artwork: Twemoji, licensed CC-BY 4.0.