I upgraded to Windows 8.1 because my sister insisted it was realy cool (I regret that now), but now what I play the game the intro is sluggish and the audio is broken, It does not seem to affect the main game, but it is annoying. Is there some way to fix it or I commited (as it seems to be) a very bad mistake?

[Edit]

Fixed, just had to use compatibility mode for Windows Vista service pack 2

I don't know if there's been a patch since your post, but I'm running Windows 8.1 64 bit and I don't have to set compatibility mode, the game runs without errors. Do you have a 64 or 32 bit OS? I think you might be missing a dependency like .NET framework or something, but I have no idea which it would be because I already have so many other games that install dependencies automatically.