well, i don't know if somebody thought about it already, but it would make the game cooler adding shaders and brightness, who would like to make it?
i have a little experience in programation but i have no freaking idea of how to get in the codified files and archives
Unlikely given the game's age, the OpenGL engine is pre-shaders.
The shading language would be GLSL. There are some quite differences to HLSL but I think it's maybe possible, if there aren't any engine limitations.
As mentioned, the game uses a pre-shader version of OpenGL, to add shader support you would need to redo a non-trivla portion of the graphics engine.