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