Despite their occasional protests to the contrary, both Nintendo and Sony have seen the pervasive mobile market take chunks of the portable gaming industry. The mobile app space burgeoned as game developers undercut each other constantly, in a race toward 99 cents that set a buck as the de facto price point for the new marketplace. This, in turn, made a massive price disparity between mobile games and their handheld competition, which tends to retail for much more. Why buy a $30 DS game, when you can buy 30 games for the same price?

However, we're now seeing yet another race all the way to the bottom: free. Even as the PC space is largely adopting a free-to-play, microtransaction-driven business model, the shift is similarly occurring in the mobile market. Recent F2P hits have started a run of similar titles, with some paid apps adopting a free-to-play option.

The change began subtly. Rovio's breakout hit Angry Birds may have stuck near the top of the Top Paid Apps charts, but the Top Grossing arena was ruled by little blue men early last year. Smurfs Village spent months as the Top Grossing app, no doubt bolstered by co-marketing for the then-upcoming film. Still, the free app had an inviting price point, and even a few 99 cent purchases per user would easily push it above the revenue for a one-time dollar fee. Then, Tiny Tower became the talk of the iOS App Store blogosphere, using a similar model inspired by social gaming on Facebook, even garnering recognition as Apple's official Game of the Year.