There are currently 41 playable civilizations in Caveman2Cosmos. Each civilization has between one and five leaders.

Unlike Vanilla Civilization IV, there are no longer unique units or buildings associated to a particular civilization, the former been triggered by cultures and the latter been removed from the game.

There are also two non-playable civilizations: the Barbarian State  and the Minor Nation.

On top of these default civilizations, there are a number of custom civilizations and civilization packs available for download.

Game concepts
Civilizations · Leaders · Traits · Technologies · Units · Heroes · Promotions · Specialists · Buildings · Wonders (world · national · natural · projects · cultures) · Civics · Religions · Corporations · Terrains · Terrain features · Bonuses (map · cultural · other) · Improvements · Routes