I want to put 8bit music in my game do I have to remix the original sound or can I get it (the 8bit version) from the internet ??
If you can make a midi of the original track, you can run it through this program to get a basic chiptune
http://www.geocities.co.jp/SiliconValley-SanJose/8700/P/GsorigE.htm
There's a bunch of thirsty musicians out there tbh, I'm sure you could find someone to do a quick version in a program called 'famitracker'
both programs mentioned are free. good luck!