You would enter the Gungeon, a dungeon that is filled to the brim with all types of guns and bizarre gun-like weapons, the Gungeon is very different from other dungeons as it has eternally shifting ooms and walls which are different for everybody who enters the Gungeon and makes sure no visit is ever the same, also with loot, hidden secrets, and much more, but you have come to the Dungeon for one thing alone, the gun that can kill the past, in order to fix your most terrible mistake you made.