I've been working on porting my game from XNA to C++ so that it will run on the iPhone/iPad/etc. As part of that I made a clone of XNA 4.0, except in C++ and OpenGL. So here it is.

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

The API is intended to match the XNA API as closely as possible, though there are plenty of places where it doesn't, since I was only focusing on the particular methods that my game uses. But it generally works pretty well. So far I've got it running on Windows, Linux, MacOSX, and the iPhone simulator.

It's still kind of raw, but I hope it's useful. Opinions welcome!

What kind of implementation are you talking here? Is it a direct drop-in like MonoGame? How's the performance?

Looks very interesting.

What kind of implementation are you talking here? Is it a direct drop-in like MonoGame? How's the performance?

I've never used MonoGame, but it sounds like a similar idea. Although XNA and MonoGame are in C# and NXNA is in C++, so NXNA will never really be a completely drop-in replacement. But yeah, the API is intended to (eventually) be as close as possible.

I'm not really sure how performance compares to XNA. I've only tested it on PCs, never an actual device, and my game doesn't tax the hardware enough to know. I'm sure it could be improved, but for me, performance has been fine so far.