Overdrive is practically two games in one. First, you have the arcade game, where you have to race against a succession of drivers, each better than the one before, until you reach the final challenge and claim victory. The second game is a time-trials challenge, where you have to race a variety of vehicles over a number of courses against the clock. This is slightly easier than the arcade version and gives you the option to get some practice in.
You have four different cars to control in Overdrive, ranging from a GP to a Super sports car. All have their own strengths and weaknesses, as you would expect. The controls are very responsive, and it goes without saying that it's incredibly playable. What makes it so tough is the speed. Everything just whips along at such a rate that it's often hard to anticipate corners, and you end up careering all over the shop. Overdrive lets you link up two machines via the null modem cable.
Of course, it can't all be good, or it would have got a mark of 100%. The biggest problem is the horrendous loading times. As the levels vary greatly, the game has to load in complete graphics for each race, which can take a lot longer than the race itself in some cases!