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