Mexica plots the development of the city of Tenochtitlan on an island in Lake Texcoco. Players attempt to partition it into districts, place buildings, and construct canals.

Districts are formed by completely surrounding areas of the island with water and then placing a District marker. The player who founds a district scores points immediately.

In the scoring phases of the game, players score points based upon their dominance in each District.

Mexica is the second game of the Mask Trilogy