Exit the Gungeon: How to Get the Hat “The Beast” and the “Beastmaster” Achievement

Pause the game and go to
Options > Game
(The wrench icon followed by the bullet kin icon)
Turn “Beastmode” on.

Note: If we talk to the left guard at the entrance after we attempt to exit the Gungeon, he’ll ask us if we beat the game. Responding “Yes” will lead him/her/it telling you that you are ready for beastmode.

Once you’ve turned Beastmode on, Exit the Gungeon and defeat the level five boss, The Last Dragun.

Once you beat the game, you should get the achievement “Win”.

Return to the settings and change Beastmode from “ON” to “LVL 2”.

Note: If we talk to the left guard after beating the game with Beastmode on, we’ll get similar dialogue but we’ll be told about Beastmode level two.

Once you’ve turned Beastmode to “LVL 2”, you have to beat the game again.

Once you beat the game with Beastmode Level 2, return to the Under-Breach and talk to the left guard again. The guard will congratulate you and the character you are playing as will equip the hat “The Beast”.

IMPORTANT SIDENOTE[/b]
If you don’t haven’t yet unlocked Hattori, you will not be able to unequip the hat until for the character equipped with it until you do so.