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