I think most developers are interested in the engine development (a known quantity) but when it comes to the art assets (3D models, animations, textures, level design) that seems like a giant unknown to me.
I would enjoy working on a rendering engine, but if I had to model characters and animate them, I think I'd release the game 6 weeks before my 97th birthday.
If you have talent in all the required spots to do this, I'd agree with the other poster... so 2 or 3 proof of concepts in the app store to hone your skills.
1. Game 1, simple terrain traversal game. Get used to open-world rendering.
2. Game 2, character-focused game with stats. Get used to modeling and animation.
3. <some more stuff>
4. Game 4, Skyrim for iOS
Step #3 is critical; don't skip that :)