I have been asking a lot of people to do a song but no one does:( I have listened to hundreds of game songs, personally I think kirby and sonic songs are good for hard charts. Try this one first you can download it free here:
http://www.last.fm/music/FFmusic+Dj/_/Ahead+On+Our+Rave+(On+Our+Way)

Make a cool stepchart and ill send you some links for some other good game songs, just recently i got the complete flashbulb and dj sharpnel (all the albums) on utorrents so I got them all:) Some of the flashbulb songs would make good stepcharts.

here is a kick ass kirby song:
http://www.last.fm/music/DarkeSword/_/Final+Flight+~+Theme+of+Final+Star
might want to use audacity to edit out the slow parts:P I have made some dj sharpnel/m1dy remixes if your interest. I picked out the hardest parts from all their songs and made them into 2 evil songs and 1 lighter song.