Puzzle zc5Vl_M — ELO 2499
This is a Black-to-move puzzle rated 2499 ELO. The first move is b4b3, tagged with 10 interpretable concepts and Lichess themes: advancedPawn, advantage, attraction.
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Position
Black to move. ELO 2499. Themes: advancedPawn, advantage, attraction, endgame, promotion, rookEndgame, veryLong.
FEN: 8/1kp5/5P1R/p6p/1p6/4K2P/r4P2/8 b - - 0 37
Show solution (10 ply)
Try to find the move yourself first — look for the rarest concept firing on this position before peeking. Solution sequence: b4b3 f6f7 b3b2 f7f8q b2b1q f8f3 b7a7 h6a6 a7a6 f3a8
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 Pawn endgame with kings centrally placed and passed pawns on both flanks…, which appears in only 50 of our 9,950 puzzles (0.50%). 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 2499 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?
2499 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 b4b3.
What concepts does it train?
10 SAE-derived patterns including Detects endgame positions with an advanced passed pawn and…; Detects an empty square on the first rank that is attacked…; Advanced passed pawn on the 6th or 7th rank close to….
Can I attempt it without an account?
Yes — Climbchess requires no signup or email. Click the trainer link to play the position interactively.