ricacr Although using the standard SDK is C and SDL you can use one of these:
A well established game programming library, (hence many existing games can now be ported) which is also available on Windows, Mac, Linux, etc. allegro homepage
Now also available for the gp2x: download
Pygame is a Python based SDL interface. For those that hate C.
rlyeh's Minimal Library
As alternative to SDL you can use rlyeh's minimal library. On how to use it/set it up see rlyeh's Minimal Library SDK.
LibGP2x is in the same vain as the above minimal library. Provides access to the screen, controls and second processor.
Ruby and Rubygame are a Ruby based SDL interface. An altenative to C and Python.
Writing directly to the framebuffer device
EDGELIB is a commercial mobile game engine written from scratch in C++ originally created for PDA's and mobile phones. As of version 2.50 a GP2X version is also available. Free for non-commercial use. The EDGELIB product website is located at http://www.edgelib.com.
FPC4GP2X FPC4GP2X uses the FreePascal ( http://www.freepascal.org ) compiler and JEDI-SDL http://jedi-sdl.sourceforge.net ( the Pascal headers for SDL, which works on Win32, Linux, MacOS X, GBA and now GP2X ). Code once then compile and deploy on many is our aim. More information about FPC4GP2X can be found at http://fpc4gp2x.eonclash.com/
GLBASIC is an extension of the BASIC programming language( http://www.glbasic.com ) that compiles to high speed machine code. Although games programming is the primary target market, almost any type of multimedia application can programmed and its use of in-line C allows almost infinite extensibility. GLBASIC is a commercial project that is free for schools.