Kinonk is a Pentominoes program written in C++. Pentominoes is a two-player board game where the goal is to be the last player to put a pentomino (a piece composed of five squares) on the board. Kinonk can also play Katamino, a variant of pentominoes. It uses a simple brute force algorithm, and can play any position perfectly if given enough time. You can constrain its time by giving an arbitrary time limit, or simply let it analyze everything. Charts can be generated using a Perl script included in the package.
MUSoSu is a free software project for playing, solving, and generating Sudoku games. It is written in Java and emphasizes both solving Sudokus simulating methods used by hyman solvers and generating Sudoku problems that don't require trial and error methods to be solved. MUSoSu is partly themeable and platform independent.
Tombs of the Asciiroth is a puzzle/RPG/roguelike game you can either play in a Web browser or as an Adobe AIR application (available for Mac, Windows, and Linux). It is simple to play compared to most roguelikes, but the provided scenario should allow for some in depth game play. A map editor also exists to create new scenarios.