What is 三步虎, the 'three-step tiger' opening system?
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
三步虎 ("three-step tiger") is a rapid development pattern on one wing: a horse comes out, the cannon on that wing moves to the edge file, and the chariot slides from the corner onto the file the horse and cannon just left. Black often uses it against the Central Cannon, though Red can play it too. The name reflects the speed of the plan: an active chariot in three moves.
Why speed is the whole point
All three moves serve the chariot: the horse and the cannon step off its file, and by the third move it stands on an open file, often facing the opponent's chariot. Getting a chariot into play that quickly can catch a slower-developing opponent before their own pieces are ready to resist it. The cost is a cannon on the edge, usually less active than one nearer the centre.
What can go wrong with rushing it
Playing the three moves mechanically, without checking what the opponent is actually doing in response, can walk into a concrete threat the plan never accounted for. The speed is only valuable if each of the three moves is still the best available response to the position in front of you, not a fixed sequence played on autopilot.
Related questions
Is 三步虎 the same as Screen Horses?
No. Screen Horses brings out both horses to guard the centre; 三步虎 concentrates on getting one wing's chariot out fast.
Is this considered an aggressive or a solid system?
Aggressive; it prioritises quick activity over the kind of unhurried structural solidity a system like 飛相局 offers.
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