Random tactics puzzles train everything equally. But you don't fail equally at everything. BlackboxChess finds which tactical patterns are actually costing you points across your game history, then builds a targeted drill set from positions in your own games.
Puzzle platforms give you a random mix of forks, pins, skewers, back rank mates, and everything else. That's fine for broad skill development. But if 80% of your tactical losses come from one specific pattern — say, missing back rank threats when you're focused on an attack — then random puzzles are a slow way to fix that problem.
You'd get more out of 10 positions that match your specific failure mode than 100 random puzzles across all categories.
Stockfish runs across your last 10 to 100 games. Positions where you missed a tactic or left a piece hanging get flagged and classified. The system tracks hanging pieces and back rank vulnerabilities specifically as tactical categories, scored by how much each one costs you per occurrence.
The full report also includes real game examples: the exact position, what you played, and what the engine says was the better move. These aren't reconstructed teaching positions. They're your actual games.
With the $10 full report, you also get a targeted drill course generated from your game history. About 10 positions from your actual games where your top weakness appeared. The goal is pattern recognition training on the specific type of position that catches you, not volume for its own sake.
This is what makes the analysis actionable beyond the diagnosis.
The free tier runs on your last 10 games and shows your top weakness category. No account or card needed. Enough to confirm whether the diagnosis is accurate before going further.