GTA V alternative for younger kids?

My son's best friend is 6 and his mom lets him play GTA V with other people - flying helicopters, racing cars, etc - but I just don't feel comfortable buying the game for our son considering everything else that's in it. I'm looking for an alternative that doesn't have all the cussing, sexualization, etc.

Added (1). We have Little Big Planet and Minecraft they can play together already.

Tell him to do what I did as a kid, go outside.

Most alternatives which are still decent are usually the same rating (M, MA, R etc)