The maker of the popular mobile game Angry Birds is reporting its operating profit plummeted in 2013.  Rovio Entertainment says its profit tumbled by more than half last year and its revenue was basically flat at $216-million.  

The Finland-based company cites investments in its animation business as the reason its operating profit went from well over $106-million in 2012 down to $50.6 million last year.  

Rovio is working to adjust its business model and quickly adapt to evolving gaming trends.