Developer Stefan Brück at alea describes Saint Malo as "a light, dice-rolling strategy game in which the players draw their own city buildings, walls, and people on wipe-off boards".
In more detail, in Saint Malo players roll five dice to gain various resources; combinations of dice create enhancements like characters or buildings, which can provide additional victory points, money, or special actions, such as altering the outcome of a die roll. Players draw symbols for their holdings on erasable boards showing a grids of their cities to create individual towns. Players could build storehouses on particular squares, for example, then place a merchant nearby to gain money each turn. Another important character is the soldier; players must acquire these to defend themselves from pirate attacks that can decimate their towns.