Mörderschwestern (2011)

After 20 years in prison, the former angel of death at Lainz hospital has been released, and she now works in the Prater amusement park, at a restaurant that specializes in roast knuckle of pork. Observing the guests and how they behave reawaken old emotions, and she poisons a pork knuckle to punish the happy people. The movie audience can use their remote control devices to decide who dies.