Here is the full list of all 23 Afterparty achievements.
Intentionally lose to Satan.
Recruit the Drunk Idiot Demon for Satan's final challenge.
Make friends with Wormhorn.
Play as Lola after fighting with Milo.
Reunite Beth and Asmodeus.
Play a perfect stacking game.
Get an Invite to Satan's from Lynda.
Don't miss a step while dancing.
Intentionally curse twenty times.
Play a perfect game of beer pong.
Drink a lot of booze.
Waste 20 minutes on Bicker.
Beat Satan and earn your way back home.
Make friends with Sam.
Reunite Milo and Lola.
Play as Milo after fighting with Lola.
Get Asmodeus's Seal of Approval.
Get Apollyon's Seal of Approval.
Try 20 different drink types.
Pet the damn dog.
Get an Invite to Satan's from Fela.
Kick off your adventure in Hell.
Fail to beat Satan.