Global Diplomacy (GD) and Age of Discovery (AoD) are two variants of a play-by-emailwargame, run by E-Mail Games. The games simulate strategic-levelwarfare and diplomacy at a late-19th Century (c.1880) technology level. The smallest units are of corps and squadron size. Whereas Global Diplomacy (and Global Diplomacy 2) attempt to simulate a world war, on Earth during the era of New Imperialism, Age of Discovery uses a randomly created map and world. There are a couple other small differences between the two games.
screenshot of AOD