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