A friend and I started playing tic-tac-toe today at lunch, and we tried variations in grid size, winning-sequence length and shape, number of moves in a turn. When we tried using a 6-by-6 grid, with 4 in a row (or in a square), and 2 moves per turn, it felt like there was a bit more strategy involved. It felt like a simple game of chess, my friend said.
It’s usually more fun to play with the rules than by the rules. James Carse made a similar point in his book Finite and Infinite Games.