Here is the full list of all 23 Afterparty achievements.
Intentionally curse twenty times.
Fail to beat Satan.
Make friends with Sam.
Reunite Milo and Lola.
Play as Milo after fighting with Lola.
Get Apollyon's Seal of Approval.
Waste 20 minutes on Bicker.
Get Asmodeus's Seal of Approval.
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.
Get an Invite to Satan's from Fela.
Play as Lola after fighting with Milo.
Intentionally lose to Satan.
Beat Satan and earn your way back home.
Make friends with Wormhorn.
Recruit the Drunk Idiot Demon for Satan's final challenge.
Reunite Beth and Asmodeus.
Play a perfect game of beer pong.
Play a perfect stacking game.
Drink a lot of booze.