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