Here you will find a listing of educational Open Source games.
Regular Websites
An openly developed empire-building strategy game inspired by the history of human civilization; from prehistoric times, through the stone age and on to the space age. Contains screenshots, download and installation information. - FreeCiv
http://freeciv.wikia.com/wiki/Main_Page
A free and openly developed cross-platform Sudoku puzzle game; contains download information, as well as FAQ. - Play Sudoku
http://playsudoku.sourceforge.net/
A Sudoku application for Pocket PC (Windows Mobile); generates Sudoku puzzles using six different difficulties, and more. - Pocket Sudoku
http://sourceforge.net/projects/pocketsudoku
An openly developed project based on Childsplay and it will become a program that offers various educational activities and games currently found in Childsplay. - Schools Play
http://www.schoolsplay.org/
An openly developed turn-based tactical strategy game with a fantasy theme; featuring both single-player, and online multi-player combat. Contains download and documentation information. - The Battle for Wesnoth
http://www.wesnoth.org/
An openly developed game which combines real time strategy with a first-person shooter or team play effort. Contains download and documentation information, as well as FAQ and installation instructions. - Tremulous
http://tremulous.net/
Tux Math is an openly developed educational math tutorial game for elementary school level children; stars Tux, the Linux Penguin, and players must answer math equations to shoot down comets which are falling towards their cities. - Tux Math
http://www.geekcomix.com/dm/tuxmath/
TuxMathScrabble challenges players to construct compound equations and consider multiple abstract possibilities; includes a data recorder interface for student performance assessment. - TuxMathScrabble
http://www.asymptopia.org/
TuxTyping is an educational typing tutorial game starring Tux, the Linux Penguin; player guides Tux to eat fish which are falling from the top of the screen. - TuxTyping
http://tuxtype.sf.net/