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