No need to guess folks. The Nielson report from last year has plenty of data on app usage on smartphone. Games are indeed on top.
EDIT: url to report: http://www.slideshare.net/zebs/nielsen-mobile-apps-whitepape...
EDIT: url to report: http://www.slideshare.net/zebs/nielsen-mobile-apps-whitepape...
Even if games were in some way irrelevant the statistic that they're on top is that 61% of smart phone owners reported using a game in the last 30 days.
But that's only marginally ahead of weather apps at 55% (and the Weather Channel 3rd party app was one of the most popular apps overall), maps at 50%, social at 49% (all 3rd party).
The overall picture is of a lot of people using a lot of apps, many of which are the core 10.