價格：免費
檔案大小：15 MB
版本需求：需要 iOS 8.0 或以上版本。與 iPhone、iPad 及 iPod touch 相容。
支援語言：英語
Synonyms of this game name:
- Tick-tack-toe, tic-tac-toe, tick-tat-toe, or tit-tat-toe (United States, Canada)
- Noughts and crosses or naughts and crosses (United Kingdom, Republic of Ireland, Australia, New Zealand, South Africa, Zimbabwe)
- Exy-ozys, xsie-osies (verbal name only) (Northern Ireland)
- Xs and Os (Egypt, Republic of Ireland, Canada, Zimbabwe)
More detailedly, to guarantee a draw, O should adopt the following strategies:
If X plays corner opening move (best move for them), O should take center, and then an edge, forcing X to block in the next move. This will stop any forks from happening. When both X and O are perfect players and X chooses to start by marking a corner, O takes the center, and X takes the corner opposite the original. In that case, O is free to choose any edge as its second move. However, if X is not a perfect player and has played a corner and then an edge, O should not play the opposite edge as its second move, because then X is not forced to block in the next move and can fork.
If X plays edge opening move, O should take center, and then follow the above list of priorities, mainly paying attention to block forks.
If X plays center opening move, O should take corner, and then follow the above list of priorities, mainly paying attention to block forks.
When X plays corner first (best move for them), and O is not a perfect player, the following may happen:
If O responds with a center mark (best move for them), a perfect X player will take the corner opposite the original. Then O should play an edge. However, if O plays a corner as its second move, a perfect X player will mark the remaining corner, blocking O's 3-in-a-row and making their own fork.
If O responds with a corner mark, X is guaranteed to win, by simply taking any of the other two corners and then the last, a fork. (since when X takes the third corner, O can only take the position between the two X's. Then X can take the only remaining corner to win)
If O responds with an edge mark, X is guaranteed to win, by taking center, then O can only take the corner opposite the corner which X plays first. Then X can take a corner to win.
支援平台：iPhone, iPad