Here is the full list of all 40 Bitardia achievements.
The base game contains 37 achievements, and there is 1 DLC pack containing 3 achievements.
Finish the "Hotline Bitardia" quest
Agree to work on Abu
Finish the "Fifth Column" quest
Finish the "QT 3.14" quest
Buy a pillow for anon
You have finished the note-finding mission
Served a term in prison
Get arrested for spoiling the stand
Break out of prison
Get to jail after showing the video
Take the builder quest
Kill Cancer on the first mission
Pick Anon Mask
Pick Cancer Mask
Kill anons on the first mission
Kill cancer on the first mission
Take the guard quest
Explode the building
Get to jail after talking to police
Get to jail after entering the police station
Get to jail while taking the camera
You didn't accept the note-finding mission
Rob the caravan
Get some cash on arena
More than 100 killed on arena
Rescue the hostage
Beat anon in cards
To die, refusing to work on the Abu
Finish a halloween-quests
Finish the "Winter is coming" quest
Finish the "Missing part" quest
Finish the "Fifth wheel" quest
Take care of the hospital
Return anon's debt
Take care of the bank
Agree to work for resistance