Pulled live from Lichess's public masters database, not a theory set Rookie maintains itself.
Couldn't reach the masters database just now (Lichess may be rate-limiting or briefly unavailable). This isn't the same as "no theory here", try again in a moment.
This explorer pulls directly from Lichess's masters database — millions of games played by titled players in real over-the-board tournaments, not engine games or club play. The percentages next to each move show how often masters chose it from this exact position, and the white/draw/black bar shows how those games actually turned out from here, so you can see not just what's played but how well it tends to score.
Play any move on the board, or click one of the listed candidate moves, to walk deeper into a line and see the masters' database answer at every single step, the way you'd explore an opening on Lichess itself. Useful for checking whether a move you played (or are considering) is known theory, or for finding out exactly where a line stops being "book" and becomes original thinking.