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