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