Atic Atac takes place within a flip-screen castle in which the player must seek out the "Golden Key of ACG".
The player can choose from three different characters:
The choice is not only cosmetic - each character has access to a secret passage unique to them, meaning that navigating the castle is different for each character. In addition, the Serf is the only character to have momentum and will continue to run briefly, unlike the others who come to a dead stop.
Similar to other Ultimate games, common enemies appear in each room after the player has entered and randomly attack the player. There are also enemies who cannot be killed and must be avoided. These generally guard pieces of the ACG key, or attack the player.
Doors randomly open and close in each room, and it is possible to be briefly trapped in a room whilst the life meter ticks down. Upon death the player is replaced by a gravestone which stays in place for the remainder of the game.