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.
Scorched 3D is a modernization of the classic DOS game Scorched Earth ("The Mother Of All Games"). It incorporates a lively three dimensional landscape that includes animated jets, naval vessels, water, and even birds, in addition to detailed tanks and projectiles. Other enhancements include LAN and Internet play and music.
SpaceZero is a RTS 2D space combat game for two players over a network. The objective is to conquer the space, defeating all enemies. At the starting point, you have only one ship and one planet, but you have money to buy more ships to conquer more planets. All the ships can be controlled by the computer (automatic mode) or by the player (manual mode). You can easily change among your ships, controlling all of them independently.
Widelands is an economic and military simulation game. The map is shown in parallel perspective with 3-dimensional terrain. Buildings and units are animated. The player controls a tribe. Land is claimed and held by military presence and then used to build an economy to support military expansion and confrontation. The project is a work in progress where much remains to be done; computer players and multiplayer are in very early stages of development. Some features that have already been implemented are exploration, fog of war, sound effects, background music, adjustable simulation speed, a few tutorial campaigns, translations to several languages, and a map editor.
Netrek is a 16-player two-dimensional graphical real-time battle simulation with a Star Trek theme. A game is divided into two teams of 8 players (or fewer), who dogfight each other and attempt to conquer each other's planets. Netrek is the probably the first video game which can accurately be described as a "sport". It has more in common with basketball than with arcade games or Quake. Its vast and expanding array of tactics and strategies allows for many different play styles; the best players are the ones who think fastest, not necessarily the ones who twitch most effectively.