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