0 A.D. (pronounced "zero ey-dee") is a cross-platform real-time strategy (RTS) game of ancient warfare. It's a historically-based war/economy game that allows players to relive or rewrite the history of ancient civilizations, each depicted at their peak of economic growth and military prowess.
Bitfighter is a game that feels a little like Asteroids on steroids. It's a multiplayer space-based combat and strategy game, featuring customized ships, multiple game modes, cool retro graphics, and smooth network play. It also includes a full featured level editor, Lua scriptable bots, and other cool features. It has a very active development team, so the game keeps improving.
Unknown Horizons is a 2D realtime strategy simulation with an emphasis on economy and city building. Expand your small settlement to a strong and wealthy colony, collect taxes and supply your inhabitants with valuable goods. Increase your power with a well balanced economy and with strategic trade and diplomacy.
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.
In Assassin of the Underdark, you take a custom player character through the underdark. RPG elements are included in the form of weaponry, items, and spells. There are scripts to print Python character files, resource management, and a widget system. A plugins directory is loaded at program start, and there's a Python shell window widget for testing out scripts.