Here is the full list of all 27 Hollow achievements.
Encounter Reaper for the first time.
Slain first flying enemy.
Fix generator with fuse.
Fire-off all hands of wanton, than finish it with a headshot.
Collect all available weapons.
Slain first Puker.
Kill wanton using gas tanks only.
Blow first destructible using gas tank.
Slain first wanton.
Kill wanton with single shot in a head.
Find all documents and notes.
Find all girl posters.
Find all collectable radios.
Sync all generators.
Get killed more than 50 times.
Kill all monsters available in a game.
First bullet for Reaper.
Get caught by Reaper.
Finish Hollow game.
Unlock ending A.
Unlock ending B.
Finish game at HARD difficulty.
Finish game at HARD difficulty under 3 hours and do not use Save Discs.
Go trouth all hallucination events in Laboratories.
Escape planet dream and get back to Shakhter-One deck.
Find way out of Cable Maze.
Kill burning Puker.