Here is the full list of all 18 OTXO achievements.
Collect all guns
Collect everything from the gachapon machines
Destroy the Heart
Order the ANIMAL drink at the bar
Kill 15 enemies with doors without dying
Kill 50 enemies with grenades
Play fetch
Clear a room without using Focus
Roll over 100 times
Kill an enemy with a thrown magazine
Die for the first time
Go fishing
Vault over 50 times
Clear a room by only kicking
Clear a run on Impossible Mode
Kill 50 enemies with kunai
Unlock all drinks
Clear a full run without taking any drinks