SimWar is a 2D multi-player realtime strategy game (in the style of C&C) designed for local-area networks. It includes additional features such as line of sight and hidden units. Emphasis is on an easy setup and a quick start.
Massively Multiplayer Space Trading and Combat game. This is an online strategy game, not a 3D space sim. Incorporating ideas from games such as Stars!, SE3, MOO, Tradewars, MUD/MOOs, Dune II, SimCity.
COTB is a space sim putting you player in command of a capital spaceship in a realistic universe. You have a crew with different skills for the jobs of Pilot, Gunner, Engineer, Scanning, Repair etc. and control the ship by giving orders. See Wiki.