[mnem]

I would be quite surprised if most App Store games were created with Unity - it's expensive and (comparatively) cumbersome to develop in, especially if you're just using 2D graphics (even with the fancy new Unity2D stuff). I can't find any stats on mobile game engine use though, which is a shame because I think it would be interesting to know.

When creating Unity3D games, you have to be reasonably careful about garbage collection - lots of nasty performance dips result if you assume that it just works. Generally you have to cobble together a mixture of object pools and statements attempting to force collection at a convenient point in the game flow amongst other things. It would be quite nice if you could turn it off for specific portions of code :)

[mnem]

Found some interesting statistics on this site: http://www.iresearchchina.com/views/5604.html

I suspect to get anything more detailed you may have to purchase a paid report from one of the various analytics companies.

Sorry, I've wandered rather off topic...

[bad_user]

Unity uses an older Mono (2.10 I believe) which has a poor GC that's not even deterministic, so you can easily suffer memory leaks. It is also not generational. Newer versions of Mono come with a much better GC.