What is a 'practical try' tactic, and when is it worth playing even if not fully sound?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
A practical try is a move or sequence that relies on the difficulty of finding the correct defence, rather than on being objectively sound, and it is worth more the less time or comfort your opponent has to work it out. It is a deliberate bet on human error, not a claim that the line holds against perfect play.
When a practical try is a reasonable choice
Under time pressure, against a visibly rattled or much weaker opponent, or in a position that is already lost by ordinary means, a move that is only correct if the opponent finds one precise reply can be worth far more than its objective soundness suggests. This overlaps directly with finding swindles in a lost position, which is really a specific application of the same idea.
When it is the wrong choice instead
Against a calm, strong opponent with plenty of time, or in a position that is objectively fine without needing a gamble, playing a practical try instead of the objectively best move usually just throws away real chances for a smaller one. Reserve it for situations where the objective evaluation is already bad or the conditions genuinely favour an error.
Related questions
Is this the same as a speculative sacrifice?
Overlapping but broader: a speculative sacrifice is one kind of practical try, but the idea also covers quiet moves and repetitions that simply set a hard practical problem.
Do strong players use practical tries deliberately?
Yes, particularly in must-win situations or fast time controls, where the gap between objective best and practically hardest matters more than usual.
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