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.
Empire is a game that is played against human opponents over a computer network. It is possible for a game to last from a few hours to many months. While the common goal of an Empire player is to win, there is no clear-cut definition of what winning is. Players may seek to achieve whatever goals they want to achieve.
Space Exploration: Serpens Sector is a very long-running project to make a space exploration game in the vein of Strange Adventures, Star Control, and others. It's gone through a number of iterations and refinements over the years. In its current state, it is now gameplay-complete. The gameplay focuses on making interesting decisions balancing risk, reward, limited resources, the morale of your crew, and your reputation with the alien factions of the sector. The gameplay does not focus on combat.
Gigalomania is a 2D real time strategy game that is a clone of Mega-Lo-Mania. The gameplay consists of researching and developing new technology with which to conquer your enemies, from rocks and sticks to nuclear weapons and spaceships. You can advance through ten different ages, from the stone age to the future. There are 28 different maps to play through. The game is still under development, but is entirely playable in its current state.
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.
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.