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