I'm usually not that big on the whole 'natural play spaces' thing because most of them look too much like workout equipment and don't have much room for imaginative play- but this one actually looks great!
Need a border / fence idea? Here's a recycled pallet fence that offers a way to grow more while also. pinned with Pinvolve Could do something similar against the backyard fence. Needs to be low maint. Grass, not ivy