I've done a bit of sampling. There's a limited amount you can legally do without buying licenses though. Personally I think it would be best to follow the overall vibe of the track you're looking to recreate, but avoid sampling it. It would be unique to your game then too. I think we'd need to know more about the game before creating a soundtrack for it. If it's an 80s style game, then we could use old analogue synths to get it sounding authentic.