Puzzle t1qUJ_M — ELO 2459
This is a White-to-move puzzle rated 2459 ELO. The first move is a3b3, tagged with 10 interpretable concepts and Lichess themes: endgame, hookMate, mate.
Free forever · no email · no signup · delete data anytime.
Position
White to move. ELO 2459. Themes: endgame, hookMate, mate, mateIn4, sacrifice, veryLong.
FEN: 1kr5/5R2/Q2p3p/1p1Pp1p1/1P6/K6P/2r1N1P1/1n6 w - - 3 41
Show solution (8 ply)
Try to find the move yourself first — look for the rarest concept firing on this position before peeking. Solution sequence: a3b3 b1d2 b3a3 c8c3 e2c3 d2c4 a3b3 c2b2
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 complex tactical positions where the side to move has undeveloped or…, which appears in only 174 of our 9,950 puzzles (1.75%). 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 2459 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?
2459 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 a3b3.
What concepts does it train?
10 SAE-derived patterns including A queen actively placed on an open rank or file relative…; Detects a king on a square with few (0-2) friendly…; Detects a piece (king, knight, or bishop) on a corner….
Can I attempt it without an account?
Yes — Climbchess requires no signup or email. Click the trainer link to play the position interactively.