The goal
Two players take turns placing marks on the intersections of the board — X in red, O in blue. X always moves first. The first player to line up five in a row — horizontally, vertically, or diagonally — wins.
Reading threats
Four in a row (an open or half-open four) wins next turn unless it's blocked immediately — treat every four as a forced move.
An open three (three in a row with space on both ends) becomes an unstoppable four if ignored. Block it early, or answer it with a bigger threat of your own.
Priority order each turn: ① Can I win now? ② Must I block a win? ③ Can I make a double threat? ④ Otherwise, build toward the center.
The double threat (fork)
The main winning idea. Create two open threes at once — your opponent can only block one, and the other becomes a winning four. Most puzzles in the trainer are about spotting forks or converting them.
Openings
The center intersection is the strongest first move — it touches the most lines. Early on, keep your marks connected and diagonal-friendly; scattered marks create no threats.
Clocks & rating
Timed games use a Fischer increment — you gain a few seconds back after each move. Ranked games (online & matchmaking) adjust your ELO rating; casual computer games never do.
Analyze tab
During any game, the Analyze tab shows a live evaluation bar, the active threats on the board, and can reveal a best-move hint if you're stuck.
