Instructions in game. All levels are possible! Activate slow mode = S (If activated level 5 and 7 aren't possible) Deactivate slow mode = N T = Activate/deactivate turbo mode. Be sure you open this each time you activate/deactivate this.
The first 4 levels are very easy but after level 4 the difficulty becomes a lot higher. This platformer uses a code that I've not seen before (and I'm suprised it's actually working). It can sometimes be buggy around corners of the platforms.