Bitfighter is a free multi-player 2-D space combat game with dual-axes controls. It's a team-based strategy game featuring retro vector graphics and customizable ships. It's fast, fun, and frenetic.

FreeOrion is a free, open source, turn-based space empire and galactic conquest (4X) computer game being designed and built by the FreeOrion project. FreeOrion is inspired by the tradition of the Master of Orion games, but is not a clone or remake of that series or any other game.

Hedgewars is a turn based strategy game but the real buzz is from watching the devastation caused by those pesky hedgehogs with those fantastic weapons.

Each player controls a team of several hedgehogs. During the course of the game, players take turns with one of their hedgehogs. They then use whatever tools and weapons are available to attack and kill the opponents' hedgehogs, thereby winning the game. Hedgehogs may move around the terrain in a variety of ways, normally by walking and jumping but also by using particular tools such as the "Rope" or "Parachute", to move to otherwise inaccessible areas.

A 2D space trading and combat game, in a similar vein to Escape Velocity.