After the main story is completed, the player may continue to play the game in a new area called The Eternal Corridor, which consists on a near infinite area where new monsters that were unavailable in the main game can be found in this new area. Those areas are randomly generated "rooms", which are made of straight paths, occasionally dividing into two paths. Only one route leads to the end of the room. Once the player finds the "end" of the room they proceed to the next in the corridor. These randomly generated "rooms" supposedly go on indefinitely.
There are wild Minions residing in the Eternal Corridor. Their experience level increases as the player progresses through the corridor. This continues on and on thus making it harder to progress through the corridors. There are also boss-like Minions that can drop special "skins" to be applied in the player's Minions. Those skins have no purpose other than cosmetic.
The player can also have access to new items and equipment's. However, the player cannot access the other areas in the game, instead being stuck in the corridor forever (hence it is recommended to keep a separate save file for this).