Conquest of Elysium 3 is an old school fantasy strategy game. You explore your surroundings conquer locations that provides the resources you need. Resources needed vary much depending on what character you are, e.g. the high priestess need places where she can gather human sacrifices, the baron needs places where tax can be collected and where iron can be mined. These resources can then be used for magic rituals and troop recruitments. The main differentiator for this game is the amount of features and special abilities that can be used.
The game can be played on Windows, Linux (x86 and raspberry pi) and Mac OSX (intel and powerpc).
This is a screenshot taken from a multiplayer game. The last vestiges of the dwarven army could not hold up to the magic of three warlocks and the support of their elementals.