Global Diplomacy (GD) and Age of Discovery (AoD) are two variants of a play-by-email wargames run by Email Games. The games simulate strategic-level warfare and diplomacy at a late-19th century (c. 1880) technology level. The smallest units are of corps and squadron size. Whereas Global Diplomacy (and its sequel 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 few other small differences between the two games.
GD and AoD are derived from the board game, Diplomacy.