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