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