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