The ideal age for learning how to play games as a kid is between 1-3. Even if your child has barely learned how to walk by the age of 1, you’d be surprised how easy he or she can pick up the basic rules of a game. Of course, depending on how old your child is, the complexity of the game must vary as well. A fine example of a simple game for the youngest of ages (1 and above) would be Hokey-Pokey. Not all the kids would understand verbal instructions at that age so you’ll just have to lead by example. Show them how it’s done. Sing the Hokey Pokey song while sticking the corresponding foot out as you go and you’ll have children start following. Soon, they’ll be able to tell which is right, which is left and also learn what each body part is called.
You could even hand out rewards like candy as a form of incentive to keep things interesting. Otherwise, you can probably imagine how stale it’ll get after a while. Kids would simply start leaving or asking to play another game.