Puzzle xymbO_M — ELO 2401
This is a White-to-move puzzle rated 2401 ELO. The first move is f4c7, tagged with 10 interpretable concepts and Lichess themes: attraction, crushing, middlegame.
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Position
White to move. ELO 2401. Themes: attraction, crushing, middlegame, queensideAttack, veryLong.
FEN: k3r2r/7p/pPb2p2/2pp2n1/5Q2/2P4B/1P3PP1/R3RKNq w - - 10 27
Show solution (14 ply)
Try to find the move yourself first — look for the rarest concept firing on this position before peeking. Solution sequence: f4c7 c6b5 e1e2 b5e2 f1e1 h1g1 e1d2 g5e4 d2c2 e2d3 c2d3 c5c4 d3d4 g1f2
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 The feature detects squares attacked by exactly one white piece and at least…, which appears in only 72 of our 9,950 puzzles (0.72%). 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 2401 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?
2401 Lichess ELO. Solvers below that rating typically miss the key cue.
Which side moves first?
White to move; the first move of the solution is f4c7.
What concepts does it train?
10 SAE-derived patterns including Detects white king safely castled on the back rank…; A queen actively placed on an open rank or file relative…; White Queen on the 1st or 2nd rank, unthreatened by black….
Can I attempt it without an account?
Yes — Climbchess requires no signup or email. Click the trainer link to play the position interactively.