When I first became interested in Blender, I downloaded the then latest version, which was 2.77 and that is what I now have. At present, we do not have scripts to import Movies Game assets directly into Blender 2.77, however we can import mesh files in 2.49, save the blend and then open it in Blender 2.77. Unfortunately, the animations in a Blender 2.49 blend file are not compatible with Blender 2.77, so if you open a 2.49 blend that contains animations, the mesh files and textures are loaded okay, but the animations are lost. Likewise, if you open a Blender 2.77 blend in Blender 2.49, the mesh objects and textures are loaded okay, but any animations in the 2.77 blend will be lost.
[ 9/10/2018: The statement above that animations in a 2.49 blend file are lost if opened in blender 2.77 is incorrect. This weakens the case for rewriting the anm import script for the new blender python API, but it still seems to be worth doing as a way of learning the new blender python API. I apologize for putting out false information without adequate verification. The error may have been fortuitous since it motivated me to dive in to Blender 2.7 and get my feet wet.]
Blender 2.49 appears to be well suited to the task of creating modifications to the Movies Game and if that is all you want to do with Movies Game assets, there is little reason to upgrade to a later version because you would need to rewrite the mesh import/export and animation import/export scripts. On the other hand, if you would like to make videos or games in blender which incorporate Movies game assets, it might be desirable to use Blender 2.7 or later for that purpose. Support for Blender 2.49 is waning, while Blender 2.7 and later versions is strong. Based on my own experience, I have found that it is easier to get good looking renders in 2.7 than in 2.49. People have done some great looking stuff in 2.49, but if you are going to spend a lot of time learning about materials and lighting and animation, it would be better to invest that time in the newer version. The Blender 2.77 Game Engine seems to work better for me than the Blender 2.49 Game Engine.
The mesh import scripts originally written for 2.49 are much more complex than the animation import scripts, and we can work around that, so the only requirement is to rewrite the animation import script in order to use those animations in Blender 2.7. After some analysis, I have found that rewriting the animation import script for Blender 2.7 looks much easier than rewriting the mesh import script.
The animation import scripts I have written, are based on Gleem's legacy code, and they consist of three parts. The first part comes directly from Gleem's code and this part does not require any blender python functionality. This section parses the anm files and stores the rotation and location data for animations in a python data structure. The second part transforms the Movies Game animation data into the Blender coordinate system and the third part applies the location and rotation data to the blender object and sets key frames for each bone and prop object for the entire animation.
After working on the problem for about three days, I have a primitive version of an anm file importer for Blender 2.77. A short demo video is posted below to show some early results.