I learned about the game of three-in-a-row from H. Steinhaus's Mathematical Snapshots. It begins like tic-tac-toe, but with markers instead of Xs and Os. After 6 markers have been placed, players take turns moving their markers one space at a time vertically or horizontally, until someone has three-in-a-row (vertically, horizontally, or diagonally).
In the picture below, the six markers are placed, and it is white's turn. If each player makes their best moves, who wins?
More generally, who has the advantage, the first or second player, and what is a winning strategy? Is a stalemate or draw possible? Assuming nobody has won after the first 6 markers are placed, how many ways could black have placed the markers? What variations can you think of for this game?
What other good questions can you come up with?