Here is the full list of all 34 Eyes in the Dark achievements.
Kill 200 guardians.
Unlock the entire bookshelf.
Finish a custom 9 zone run with at least 3 anomalies.
Successfully complete Act IV.
Kill 50 guardians.
Complete a 9 zone run in under 45 minutes.
Complete a 9 zone run without equipping any items.
Complete a 9 zone run without picking up a flashlight module and/or upgrade.
Complete a 9 zone run without picking up a projectile module and/or upgrade.
Complete a 9 zone run without picking up a gadget module and/or upgrade.
Play the hidden tune in the Entrance Hall.
Successfully complete Act III.
Complete a 9 zone run without using a single projectile.
Complete a 9 zone run without upgrading a single weapon category.
Successfully defeat Blobor.
Scrap more than 50 items during a single run.
Successfully defeat Wormitor.
Successfully defeat Hermitor.
Successfully complete Act II.
Successfully defeat Arachnor & Snipor.
Fully upgrade all 3 item categories.
Clear an entire zone without taking any damage.
Successfully defeat Mothor.
Have at least 1000 sparks in a single run.
Buy all 3 items offered in the shop.
Successfully defeat Stingor.
Kill a guardian without jumping.
Successfully complete Act I.
Successfully defeat Hiveor.
Successfully defeat Broodor.
Kill a guardian without using the slingshot.
Kill a guardian without using dodge.
Successfully defeat Insector.
Complete the tutorial.