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.
Completed Manuel's Test, A Great Achievement.
Successfully Exited The Gungeon.
Mastered The Coltaur.
Mastered His Majesty's Chancellor.
Mastered The High Priest Past.
Mastered The Chamber Of Flame.
Mastered The Mecha Bullet.
Mastered The Medusalier.
Mastered The Meowitzer.
Mastered The Bolt Python.
Mastered The Armored Beholster.
Mastered The Deathvator.
Mastered The Kill Shrine.
Mastered Gungamesh.
Mastered The Lich Dragun.
Accessed All Elevator Types.
Rescued All Npcs From The Cell.
Aced Just Dessert Golf.
Aced Winchester's Game.
Completed Level 1 Boss Without Taking Damage.
Completed Level 2 Boss Without Taking Damage.
Completed Level 3 Boss Without Taking Damage.
Completed Level 4 Boss Without Taking Damage.
Completed Level 5 Boss Without Taking Damage.
Bought All Hats.
Bought All Skins.
Unlocked All Characters.
Bought Something From Bello.
Bought Something From Cadence And Ox.
Exited The Gungeon As The Pilot.
Exited The Gungeon As The Convict.
Exited The Gungeon As The Marine.
Exited The Gungeon As The Hunter.
Exited The Gungeon As The Robot.
Exited The Gungeon As The Cultist.
Exited The Gungeon As The Bullet.
Reached Max Combo.
Helped Flynt Avoid Embarassment.
Helped Goopton With Something Personal.
Upgraded Bello's Stools.
Sated Daisuke's Craving.
Gave The Old Man Something To Fiddle With.
Reunited Old Red with Daisy.
Achieved Beast Mode Level 2.
Mastered The Glocktopus.
Aced Helmet Kick.
Carried Eight Weapons At Once.