Freeciv is a multiuser reimplementation for Unix/X of the famous Microprose game of Civilization. By default, the game is an improved Civ II, but this can be customized; modpacks for near-100% compatibility with Civ I and Civ II are included. Multiuser gameplay is real-time: in each turn, all human players move concurrently. The game is designed to remain fairly playable even on poor network connections. Freeciv can also be played on standalone machines, and its AI players are a good challenge for beginners. The source code comes with the server, two X clients, and non-X clients for MS Windows and Amiga. Freeciv is released under the GNU General Public License. It is maintained by an international team of coders and enthusiasts, and is easily one of the most fun and addictive network games out there.
TripleA is a clone of the popular board game "Axis & Allies", which is a turn based strategy wargame. TripleA also acts as a game engine allowing creation of custom games with similar mechanics to Axis and Allies. It supports online play, network play, play-by-email, and single player vs AI or hot-seat. It comes with 11 different maps and the option to download more from online repositories. Most games take place during World War II, though there are mods to play other conflicts like the Napoleonic wars, or Lord of the Rings.
Chess Training Tools is a collection of chess training tools. It includes a chess visualization trainer that teaches chess visualization by drilling you on the color of a particular square, and also on your ability to tell if two squares are the same color, if two (or three) squares are on the same diagonal, if two squares are a knight move apart, or if two squares are two knight moves apart. It includes a weak chess program (called Vince) that lets you lag the display by several ply, hide all pieces or all pawns, and block out quadrants of the board. Furthermore, it includes an opening memorization trainer. The Palm & Pocket PC versions are missing the mate, opening trainer, and Vince.
UFO: Alien Invasion is a squad-based tactical strategy game in the tradition of the old X-COM PC games, but with a twist. This game combines military realism with hard science-fiction and the weirdness of an alien invasion. The carefully constructed turn-based system gives you pin-point control of your squad while maintaining a sense of pace and danger. The story is set in the year 2084. You control a secret organization charged with defending Earth from a brutal alien enemy.