Decent relative to what? These games include various card games too which in theory are even harder for AIs to beat pros at. I'd be surprised if the other minigame engines are actually decent to a skilled amateur on their hardest difficulty. The AI complexity is also irrelevant to many of these games being playable with a friend in person or online.
The length of the game is also something easily tweaked, just default the board size to 9x9 and offer 13x13 and 19x19.
The length of the game is also something easily tweaked, just default the board size to 9x9 and offer 13x13 and 19x19.