Here is the full list of all 32 Spirit of Shotgun achievements.
Reach The Nether.
Reach Tartarus.
Reach Charon’s Lighthouse
Reach Dvergrheim.
Reach Ymir’s Rest.
Reach The Desolation.
Reach The Red Cathedral.
Bring back the sunlight.
Play with a friend.
Beat your friend’s time.
Finish the game faster than one of the devs.
Beat the game under 1 hour.
Beat the game under 10 minutes.
After reaching the final level, fall all the way back to the first.
Light the first Shrine.
Light up half of the total number of shrines.
Light up every shrine.
Run out of shells.
Be saved from falling by a divine intervention.
Acquire the Dark Crash.
Acquire the Bedrock Blaster.
Acquire the Red Doom.
Acquire the Restless Redeemer.
Acquire the Slumbering Anger.
Acquire the Winter’s Grace.
Acquire the Thunderstick.
Acquire Shotcalibur.
Acquire every ancient shotgun.
Fire 100 shells.
Fire 1000 shells.
Fire 10 000 shells.
Fire 100 000 shells.