Unity 3D vs. UDK 3 for iOS

I have a couple ideas for some 3D games/apps and need to know which 3D engine to go with. I like the high-level appro开发者_StackOverflow社区ach of Unity and UDK. I have done some 2D games using cocos2d before, but I'm entirely new to the 3D world, which is why i think Unity or UDK are a good choice. I know about the differences in licensing, and i am more concerned with the learning curve instead of the licensing cost.

Plans:

• A 3D "side scroller" that goes forwards (up) instead of to the side. Third person space ship. This would primarily be for learning. Tilt to steer, tap to jump. Very simple graphics, vertex coloring would be enough.

• A 2.5D "side scroller" like the above one but with a car. This game would generate the levels randomly out of a couple prefab blocks of a certain length that fit together seamlessly.

• A 3D augmented reality display for pilots with a terrain mesh loaded from DEM data. Accelerometer and GPS access required.

Other important points:

• Must be able to tie in to In-App purchases.
• The more community content like tutorials and forums the better.
• Ability to add third party libraries like Flurry Analytics is a big plus! But i guess this isn't possible?

Which engine would you recommend for these projects, and why? Preferably, i'd like to pick one and stick with it.

You’re going to have a way, way better time developing with Unity. UDK’s got a fantastic, incredibly capable engine, but its tools don’t have the ease-of-use of Unity’s, its developer documentation leaves a lot to be desired, and the community hasn’t been using it for long enough for there to be much help to be found there. Some quick Googling suggests you can write your own Objective-C plug-ins for Unity games, so in-app purchases and third-party libraries are definitely a possibility. I think Unity’s your best bet.

What about cryengine? it free for non commercial use and also provides mono c#.

Check it out CryEngine