The 4th Stage of Forte Gigas' Fortress consists of 3 room (10 in total).

The stage starts off with the player entering the area as Mimicman appears and images himself into Dr. Fox for all characters but Fox, in which becomes Prof. Chauve. After Mimic is defeated he un-images himself and shuts-down for the player to enter the next room up.

Upon entering the darkened room it will light up and reveal 8 teleporters with different colors and letters to indicate each boss. Once all 8 are beaten the door uptop is unlocked.

As the screen scrolls into the final room the player will see Forte Gigas standing there, FG will see Mimicman again. After the door closes the pre-battle cutscene starts for each character then the battle begins after that.

FG fights like he plays, but be warned, unlike the Mimicman battles he will actually use weapons from the previous 4 games, but which game is determind by the character played. Millie will face FG I weapons, Folxbot FG II, Prof. Chauve FGIII, Dr. Fox FG IV, and FG will fight Mimicman using FG V weapons, and for the Doppleganger FG he will use weapons from all 5 games.