How do I prepare an opening specifically against a known opponent's tendencies?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws for movement, checkmate and both repetition rulings: a side that forces a repetition by perpetual check or perpetual chase loses rather than drawing. The chase half has not been validated against the official casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it before publishing.
Direct answer
Look through their recent games for a recurring weak reply or a system they play almost automatically without adapting it, then choose your own opening specifically to steer the game toward the kind of position that exposes it. This is real, useful preparation, distinct from simply picking whichever opening you personally prefer.
What is actually worth looking for
A specific defence they answer the same way regardless of what you play into it, a piece they habitually leave undeveloped, or a type of position, sharp and tactical versus slow and manoeuvring, they seem to handle less comfortably than the other. General strength is much less useful information than a specific, repeatable habit.
Why this only works with real information
Guessing at a weakness without evidence is not preparation, it is a hope. If you have no games to review, general opening principles and your own comfortable repertoire remain the better guide; see using a database to study openings for how to actually look this material up.
Related questions
Is this considered unsporting?
No, studying an opponent's public games is completely normal preparation in any competitive mind sport.
Should I always play my prepared line regardless of what happens?
No, adapt to what is actually on the board; preparation gives you a starting plan, not a script to follow blindly if the position turns out differently than expected.
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