For kart racers, nothing tops this game. There are many characters, vehicle mods, tracks, stickers, etc. to unlock; a fun and eclectic roster of characters from SEGA's classic franchises; a variety of single-player modes, game types and missions. The tracks are varied and well designed, "transforming" over the course of the race, and are full of different paths and shortcuts. I wasn't a "SEGA kid" growing up, but even for me this game oozes nostalgia and has a lot of heart. Good job, SEGA. One gripe though: fairly buggy online.
Score: 8.5 (Great!)