Hello, I'm an expert in Unity3D engine and I have been developing games for more than a year. I can build games for any platform including iphone using Unity3D. I have built several games already from scratch using Unity and some of them are attached to my portfolio so you can take a look at my works if you wish.
I have developed couple of 2D games as well(platformer shooter, side scroller), and I believe I can built your game as per your requirements.
Please knock me anytime if you want to discuss about this project further.