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