Halfbrick is celebrating the 30th anniversary of Ghostbusters (which was last year) in the latest update for Monster Dash.
It brings a new "Who You Gonna Call?" daily challenge available to play on Wednesdays and Saturdays.
In it, you can play as Dr. Peter Venkman (Bill Murray's character) and use the iconic Proton Pack. Just, er, don't cross streams, you hear?
Venkman runs across a new New York City rooftop level sucking up Slimers, as you'd expect.
If you want to play as Venkman outside of this daily challenge in other modes then you can unlock him with an IAP.