"this is the first game Rovio has taken under its wing that doesn't feature catapulted birds."
In fairness, they'd tried fifty one games before Angry Birds and they failed, commercially speaking, so wringing every possible penny out of Angry Birds does make sense of a sort. (Citation: http://www.wired.co.uk/magazine/archive/2011/04/features/how-rovio-made-angry-birds-a-winner)