actually there is an official blender 2.46 that uses python 2.4 for linux. it evidently is possible to build blender with python 2.4. if you make a 2.4 pthon build for your platform and save the game as an exe it should pack everything in. if you already use linux http://www.blender.org/download/get-blender/ get the 2.4 python version and problem solved.
Take the Python24.dll file that came with an earlier version of Blender and put it in the same folder as the game and PySonic dll. I haven’t tested it (as I am on Linux) but it should work.
PyGame is also nice for sounds, but I seem to remember liking PySonic’s audio quality better (it’s been over a year since I’ve used PySonic). However, there are licensing restrictions with the fmod sound system that PySonic uses, so make sure you’re aware of those (which you may already be).
I’ve installed Blender 2.25 and it compes with a python20.dll, I’m assuming this is python 2.0 rather than 2.4. Do you know what version of blender has python 2.4?
it sounds like you have python 2.5 installed but not 2.4. it will default to the installed version if one is found. install python 2.4 then right click on the blender version you are useing, then select open with. then find pyton 2.4 and open it with 2.4. then it should work.
you can install different versions of python al long as it is a new level. you can install 2.2, 2.3, 2.4, 2.5… but if you instal sub levels like 2.41, 2.42, 2.43. … it will default to the latest 2.4 version.
your problem now is that blender is still opening with 2.5 by default and you’ll have to use the “open with” to override the default. normally i make sure the “always use” box is unchecked the first time i open a program overriding the default just in case.