if it's an old dos game download a program called dosbox
it runs in xp. you load dosbox and map your c drive, then just run the game like you would have back in 1994
works well
otherwise if its a windows game, try and find the exe file for it (i will use game.exe as an example)
right click on game.exe and go to properties. click on the compatibility tab.
tick "run this program in compatibility mode for"
and select windows 95 or windows 98
see how you go with that