The easiest way to Detect which version of NET you have on your system is to use a little program called "NET Version Detector" by Asoft. I'm not sure if I am allowed link it here, but you can just do a search for "NET Version Detector Asoft" (exact with quotes) and it should be the first result.
The very nice this about this little program is it not only tells you which NET you have installed, but allows you to easily install other versions of NET that you may need. *Be sure to Reboot after removing or installing another or additional version of NET.
After you get your NET situation sorted out, then try to Install your game.
Hope This Helps! 🙂
