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