openage: a volunteer project to create a free engine clone of Age of Empires II, primarily aimed at POSIX platforms such as GNU/Linux, comparable in its goals to projects like OpenMW, OpenRA and OpenTTD.

openage uses the original game assets (such as sounds and graphics), but (for obvious reasons) doesn't ship them. To play, you require an original AoE II installation or AoE II: HD (wine is your friend; in the near future, setup discs will be supported).