Set in ancient Rome, Trajan is a development game in which players attempt to increase their influence and power in various areas of Roman life such as political influence, commerce, military rule, and other important parts of Roman culture.

The central mechanism of the game uses a system similar to that of the Mancala or Grain games. In Trajan, a player has six possible actions: build, trade, take tiles from the forum, use the army, influence the Senate, and place Trajan tiles on his board.