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