Here is the full list of all 31 WayDown achievements.
Defeat Satan in under 45 Minutes
Defeat Satan in under 35 Minutes
Rescued the squad Judas
Rescued the squad designated Blood Sucker
Rescued the fabled Shrinking Shotgun Surgeon
Broke the seal, and stepped into Hell
Uncovered the unnatural, subterranean Forest
Uncovered the Arcane Ruins
Rescued the squad Minister
Accessed developer Area
Defeat Satan in under 25 Minutes
You've bested Crossfit Satan! I wonder if he was the mastermind of your curse?
Bested the speaker for the trees, who was silenced long ago
Bested that totally normal and not at all weird deer
Bested the writhing Wurm of the deep
Bested the lvl 2 dwarven fighter's worst nightmare
Bested the Stranded Chuul
Bested the Acursed Foreman
Bested Phleshy, the Flesh Golem
Bested Charlie the Rat King
Bested the foremost combat expert in the Reich
Uncovered the Cursed Mines
Bested the tallest hairdo in all the Axis Powers
Bested the circus trained SS Officer
You beat the game!
Rescued the squad Projectile Trajectory Expert
Rescued designated Boom Expert
Rescued the squad Trigger Finger
Rescued the squad People-Fixer
Rescued a loose soul, cursed to wait in the dirt for all eternity
Rescued the Diesel-Punk combat drone