The Alternate Earth modules present historical settings with fantasy elements added to them. Adventures and plots are connected to real history but magic feats like augury or divine blessings really work and fantastic creatures really dwell in the most inaccessible corners of the Earth. Real world religions are represented in game, but each supplement contains hints about how to avoid offense to player beliefs.
Each module is targeted at a particular game system, shown on the cover, but all supplements are compatible with all games based on a D100 system (Basic RoleplayingTM, RuneQuestTM, Call of CthulhuTM Dark Ages etc.)