Xconq is a hex-based, multiplayer game engine with enough features to simulate good strategic and tactical wargames. There's an extensive game library with sci-fi, fantasy and standard wargames. It currently has no political system, so using the engine to create a true civ-like game wouldn't work, but for straight wargaming it's quite fun. Very good for game designers interested in 2D hex-games. The interface is in the process of switching from Tcl/Tk to SDL with ParaGUI.

License: free