Battleship
Opponent: Hunt & target · probability density
Place your fleet and duel a computer admiral that hunts with a probability density map, then closes in on every hit.
Recreational mathematics
Games
Two classic games I first wrote in C# while learning to program, rebuilt for the browser. Each computer opponent runs a small algorithm, and both pages let you watch it think.
Tic-tac-toe
Opponent: Minimax · alpha–beta pruning
The classic 3×3 game against an opponent that searches the whole game tree. On the hardest level, a draw is the best you can do.
Both games work with a mouse, a touch screen or the keyboard alone, and announce every move to screen readers. They run entirely in your browser: nothing is stored or sent.