Here is the full list of all 23 Afterparty achievements.
Intentionally lose to Satan.
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 Milo after fighting with Lola.
Intentionally curse twenty times.
Get Apollyon's Seal of Approval.
Play a perfect stacking game.
Try 20 different drink types.
Get Asmodeus's Seal of Approval.
Don't miss a step while dancing.
Drink a lot of booze.
Pet the damn dog.
Waste 20 minutes on Bicker.
Get an Invite to Satan's from Fela.
Kick off your adventure in Hell.
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.
Reunite Beth and Asmodeus.