If you are a true sonic fan who has not had the chance to play sonic CD due to the fact that it was on the ill-fated mega CD, then I fully recommend you get this and play it. It is by far the biggest (and arguably best) game in the 2D series with bigger levels, time travelling (warping to the past to save the future) and a great soundtrack (it is actually the American one, but it sounds better than the original European one did).

Otherwise, don't bother with this at all. Sonic R is just fake and tedious with awful graphics while Sonic the Fighters just makes your thumbs ache after just one match. As for the game gear games, they are just painful to play, particularly Sonic 2 with its low screen resolution making bosses almost impossible.