Location: indoor or outdoor
Materials: a scooter, ball, slide, etc-- very open-ended
Like many play skills, turn taking is something that young children need to learn. Often children are told "to share," but they don't know what that means, and "sharing" actually can mean several different things. Turn taking is the most basic version of sharing, and is something you can turn into a game with your toddlers.
Pick something that is popular among your children-- it could be a wagon or push bike, or even the slide on your climber. In this situation the game is just taking turns. You can say, "We're all going to take turns on the slide. Okay, Brian, it's your turn first. Let's watch Brian on the slide. Wow! Ok, Brian's turn is done. Now it's Norah's turn. Norah is taking her turn on the slide..." etc.
The point is to make it fun to take turns, and narrate the whole experience.
Possible Extensions: