Karting around the world varies enormously depending on where you are. In the US the racing often involves four stroke karts and oval track racing, in Australia they race anything from low horsepower 2-strokes to the fastest Formula A karts and throughout Europe it's mainly high-horsepower, high revving Italian 2-strokes just like Michael Schumacher grew up with and still drives today. So that's the direction that Michael's karting game goes with.
You begin by driving those 6 horsepower fun karts you drive at hire centers around a mix of indoor and outdoor tracks, then progress to the faster piston port ICA class karts with 22 horsepower, through to the Formula Super A beasts that the top karters race at the World Championships. These karts have engines that will spin to over 20,000 RPM (compared to around 5,000 for the average road car) and produce around 32 horsepower.