Galois is a computer game of the "falling blocks" type, but with unique features. Unlike most other games of that type, it is not limited to blocks made of four two-dimensional, square bricks: you can choose among several different brick shapes, blocks composed of more or fewer bricks, and even between two- and three-dimensional games.
Naval Battle is a tabletop/board game. It has a square playfield of rows and columns, each representing waterscape with islands, ports, shallow waters, reefs, etc. Each player gets an equal-sized fleet of war ships. The game goal is defeating the enemy, either by taking the royal port, destroying all ships and forts, or forcing the opponent to surrender.
Gambit is a graphical chess game. It's cross-platform and there are binaries for Windows, and build instructions for Linux users.