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