Every position here is one where I actually blundered, pulled from ~6,300 of my online games and 25 handwritten over-the-board scoresheets. Each was confirmed at depth 20 by Stockfish, and then every legal move in the position was scored — so whatever you play gets graded instantly, with no engine running in your browser.
Three verdicts: you repeated my blunder, you played something different but still suboptimal, or you held the position.
The interesting part is what this isn’t. In 57% of these positions there is no winning tactic at all — the best move just keeps the game alive. A normal tactics trainer can’t teach that, because the existence of the puzzle tells you something is there. Here, usually, it isn’t.