Dude, you should be proud.
Being a programmer myself, I know how much of a pain in the ass it is to recreate Sonic's movements and gravity principals. In fact, I tried to make a clone of Sonic, but it didn't come out anywhere as close as yours did. You get a 7 since it renders rather slow... 10 otherwise. You should be proud. How long did it take you to get your engine this good?