This game actually require pure skill (I don't care what you say). There are also some fakes in which the hands don't really move the shells (happens 1 in every 6 times). Time is how fast the hands move to make the next switch and speed is how fast the hands make the switch. Don't try to change the speed in the middle of it mixing or you'll screw it up. When you click begin, speed will automatically adjust itself.
