http://gamekit.org/forum/

c++ might not be for you? For Java this comes in mind:

http://code.google.com/p/libgdx/

Anyway html5 might be interesting.

develop your games in xna then make different ports to other mobile platforms using monogame. With monogame you can write games for multiple platforms using the same c# code you used to make it in xna

Corona is another one:

http://www.coronalabs.com/

develop your games in xna then make different ports to other mobile platforms using monogame. With monogame you can write games for multiple platforms using the same c# code you used to make it in xna

He will be spending alot of money that way though.

Lets start with $99 for the windows phone 7 developers license. Another $99 for the iOS dev license. He already has the relevant google license so it good there. Monogame requires monotouch (iOS) or monodroid (android) in order to function. These are $399 each. Thats $996 all together.

One important thing to consider when choosing a cross platform libraries is how much cross platform functionality they support. Many use alternative languages or don't support the full platform feature set. Others like Ximarin allow you to have a common code base but still require you to build platform specific UI Layers. Also if you are using any third party libraries in your app they may not work with the new library.

Ximarin is the one I'd consider mainly because I've got a c# background and I know how powerful c# and visual studio is. And it supports the full features of iphone and android. The main problem is $800 you'll need to pay to for the 2 licences. But even then its only useful if you design your architecture accordingly so that there is proper separation of the different layers and the correct design patterns are used.

[quote name='Zul' timestamp='1347715450' post='4980364']
Corona is another one:

http://www.coronalabs.com/

This is what I'm using. I'm extremely happy with Corona in all aspects (money / business model, stability, speed, language of Lua, simple yet powerful API, online documentation, compatibility across many mobile platforms).

To put it in perspective, I've put in just 5% of my time on learning the language and API. 95% of my time has been into what it should be -- game design, business aspects, art/asset composition and actual game programming.

For my project it is perfect. I can't comment on any 3D aspects however as I only use 2D.
[/quote]

I did a write-up about a month ago comparing the most popular Lua game engines, Moai, Corona, LOVE and Gideros. They are all great options, with different strengths and weaknesses, but Lua is just a great high level game development language.

It's one of those languages that you can learn in a weekend, then keep surprising yourself with it's power and flexibility. At it's core, it is a pretty simple language, but it is amazingly capable. Three out of four of the above languages are capable of targeting both Android and iOS, while the fourth ( Love ) has ports in the works.

Ogre, Torque 3D?