Full list of all 34 20 Minutes Till Dawn achievements. It takes around 20-25 hours to unlock all of the achievements in the base game on Windows.
The base game contains 24 achievements, and there are 8 DLC packs containing 10 achievements.
Use the Flame Cannon to survive Darkness 15.
Survive Darkness 15 with Scarlett.
Survive Darkness 15 with Shana.
Use the Revolver to survive Darkness 15.
Use the Shotgun to survive Darkness 15.
Survive Darkness 15 with Diamond.
Use Dual SMGs to survive Darkness 15.
Survive Darkness 15 with Spark.
Survive the night without getting hit.
Use the Grenade Launch to survive Darkness 15.
Survive Darkness 15 with Hina.
Survive the night without firing your gun.
Use the Crossbow to survive Darkness 15.
Survive Darkness 15 with Lilith.
Survive the night on Darkness 15.
Use the Batgun to survive Darkness 15.
Survive Darkness 15 with Abby.
Survive the night on Darkness 10.
Survive the night with Abby and the Grenade Launcher, and only using Abby's special ability to fire.
Survive the night on Darkness 5.
Survive the night with 1 Max HP at the end.
Survive the night with 8 summons as the end.
Survive the night on Darkness 1.
Survive the full 20 minutes.
Survive Darkness 15 with Yuki.
Use the Magic Bow to survive Darkness 15.
Survive Darkness 15 with Luna.
Survive Darkness 15 with Hastur
Survive Darkness 15 with Raven.
Survive Darkness 15 with Dasher.
Use the Salvo Knives to survive Darkness 15.
Use the Watering Gun to survive Darkness 15.
Use the Cyclone Sword to survive Darkness 15.
Use Katana to survive Darkness 15.