Spinning, or playing helicopter, is a kids game that toddlers start pretty young. They'll spin anywhere and have a fine time trying to pick themselves up after spinning. A weaving, disoriented toddler is hilarious to watch. Spinning could be a warning sign of a more serious disorder, but more likely, it's a case of them having just plain old fun.
Try it yourself. Spinning in circles takes balance. For toddlers who just learned to run or jump, spinning is the next logical step in learning to control their bodies. Being able to balance while spinning, or after spinning, is a skill that adults can often only appreciate from a distance. Kids love to master whatever skill they discover. Once they are start spinning, they will keep at it until it gets boring.
Spinning provides another challenge -- focusing. Focusing is dang hard after you spin for a while. Toddlers usually fall laughing on their bums, and sit and watch their world spin. Once they regain some control, they are at it again. The more they practice, the faster they gain control and focus.
Spinning is just like going on the merry-go-round or the swing. The motion is exhilarating and you don't need any special equipment. All you need is a little floor space and a mother who doesn't mind getting smashed into now and then. As far as games go, that's a pretty easy, portable option.
There could be a more serious side to your child spinning. Spinning can be a sign for autism. On it's own, it doesn't mean much. All kids spin. But excessive spinning or spinning that is accompanied by body rocking or flapping the arms, can be a sign of autism. For autistic children, spinning can be soothing. They like the repetition of the spinning motion. If you are worried that your child is spinning excessively, talk to your doctor about it and any other signs you've noticed.