Xconq is a general strategy game system. It is a complete system that includes all the components: a portable engine, graphical interfaces for Unix/Linux/X11, Macintosh, and Windows, multiple AIs, networking for multi-player games, and an extensive game library.
In addition to Xconq's "standard" game, which is similar to the classic Empire/Empire Deluxe games of years ago, the game library includes games for ancient civilizations, the Peloponnesian War, the Roman Civil War, Frederician strategy, Napoleonic strategy, Gettysburg at a brigade scale, the Russian revolution, the Normandy invasion, WWII at scales from tactical to grand strategic, Beirut street fighting, voyages of discovery, African exploration, and many others, including space and fantasy games.
Xconq's forte is turn-based strategy with overhead map views. Tiles are hexagonal, and worlds may be very large; the largest in the library is an 800x320 map of the world, a 256,000 hex monster! The game design language GDL is a declarative language where you define the units, terrain, etc, then fill in tables defining their interaction. Literally hundreds of different tables are available to the game designer. For graphics, the Xconq library includes hundreds of unit images and tiles that may be used by a game.
All this makes Xconq especially interesting for games about unusual or lesser-known strategic situations; it is unique in its ability to model the conflicts and strategies of any period in history.