What kids can do on a turf grass lawn:
Toss around a softball of football or Frisbee.
Kick around a soccer ball.
Get bored and go inside.
What kids can do in a prairie with a network of paths:
Toss around a softball or football or Frisbee and search for it among the plants when they miss.
Kick a soccer ball down the paths.
Invent their own running games on the paths.
Play hiding and seeking games with each other.
Play hiding and seeking games with objects.
Have pretend adventures and explorations.
Act out stories.
Sit in among the tall plants to read.
Sit in among the tall plants to play board games.
Sit in among the tall plants to write in a journal or draw in a sketchbook.
Listen and watch for birds.
Find insects and insect eggs and insect chewings on leaves.
Find spiders and maybe even watch them make webs.
Search for different kinds of flowers.
Find different kinds of seed heads and seed pods.
Make collections of nature things.
Find traces of wildlife.