Full list of all 47 Exit the Gungeon achievements. It takes around 30-35 hours to unlock all of the achievements in the base game on Windows.
The base game contains 44 achievements, and there is 1 DLC pack containing 3 achievements.
Bought All Hats.
Helped Goopton With Something Personal.
Sated Daisuke's Craving.
Aced Winchester's Game.
Bought All Skins.
Reunited Old Red with Daisy.
Gave The Old Man Something To Fiddle With.
Mastered Gungamesh.
Completed Level 5 Boss Without Taking Damage.
Helped Flynt Avoid Embarassment.
Aced Just Dessert Golf.
Upgraded Bello's Stools.
Rescued All Npcs From The Cell.
Mastered The Chamber Of Flame.
Exited The Gungeon As The Robot.
Exited The Gungeon As The Cultist.
Mastered The High Priest Past.
Unlocked All Characters.
Exited The Gungeon As The Bullet.
Mastered The Lich Dragun.
Mastered The Deathvator.
Mastered The Armored Beholster.
Reached Max Combo.
Exited The Gungeon As The Pilot.
Accessed All Elevator Types.
Mastered The Mecha Bullet.
Exited The Gungeon As The Convict.
Mastered The Kill Shrine.
Completed Level 3 Boss Without Taking Damage.
Mastered The Meowitzer.
Exited The Gungeon As The Hunter.
Bought Something From Bello.
Mastered The Bolt Python.
Bought Something From Cadence And Ox.
Successfully Exited The Gungeon.
Exited The Gungeon As The Marine.
Achieved Beast Mode Level 2.
Completed Level 4 Boss Without Taking Damage.
Mastered The Medusalier.
Completed Level 1 Boss Without Taking Damage.
Mastered His Majesty's Chancellor.
Mastered The Coltaur.
Completed Level 2 Boss Without Taking Damage.
Completed Manuel's Test, A Great Achievement.
Mastered The Glocktopus.
Aced Helmet Kick.
Carried Eight Weapons At Once.