Puzzle zZ4ym_M — ELO 2445
This is a Black-to-move puzzle rated 2445 ELO. The first move is b2b3, tagged with 10 interpretable concepts and Lichess themes: advancedPawn, crushing, endgame.
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Position
Black to move. ELO 2445. Themes: advancedPawn, crushing, endgame, promotion, quietMove, veryLong.
FEN: 2k5/1pp5/p5N1/6P1/P7/1P6/1r3PK1/8 b - - 0 48
Show solution (12 ply)
Try to find the move yourself first — look for the rarest concept firing on this position before peeking. Solution sequence: b2b3 g6e5 b3b6 g5g6 b6e6 g6g7 e6e8 e5g6 c8d7 g6f8 d7e7 g7g8q
Concepts that fire on this position
Our SAE pipeline tagged this position with 10 active features. Each links to a page documenting that pattern in detail.
Why this puzzle is hard
The rarest pattern firing here is Detects a king on the 7th or 8th rank, with the target square being a corner…, which appears in only 76 of our 9,950 puzzles (0.76%). Rare patterns tend to be the bottleneck — players who haven't internalised them will fail this puzzle even when their tactical calculation is otherwise solid.
The puzzle's Lichess ELO of 2445 reflects this: solvers below that rating typically miss the cue entirely.
Similar puzzles
Puzzles sharing the most concept tags with this one — a stronger signal than theme overlap because it reflects the actual patterns Leela recognises.
Train this pattern
Click through to the Climbchess trainer to attempt the position interactively against the same Leela network that tagged it. The trainer adapts difficulty using your live concept-recognition profile — it surfaces puzzles tagged with concepts you've been missing, not random brawls.
If you want the underlying methodology, the how-it-works page walks through the SAE training run, the labelling pipeline, and the puzzle-tagging procedure end-to-end.
Frequently asked
What is the rating of this puzzle?
2445 Lichess ELO. Solvers below that rating typically miss the key cue.
Which side moves first?
Black to move; the first move of the solution is b2b3.
What concepts does it train?
10 SAE-derived patterns including A square dominated by a white knight where white has equal…; Active rook delivering or threatening a decisive mating…; King on rank 2 or 7 in a simplified endgame, often with….
Can I attempt it without an account?
Yes — Climbchess requires no signup or email. Click the trainer link to play the position interactively.