Hopscotch. I would do this. Paint it and hop it. oo! you could totally easily do this for super cheap! just draw out the stencils on paper, cut them out. then put pieces of ContactPaper on the floor where you want the design. then trace the paper stencils, and the rest is probably obvious :)
Also on these boards
Anansi Playground Building designed by Mulders vandenBerk Architecten. Colouful cubes and square mosaic blackboards invites interaction and creative expression.
Get concrete pavers at big box home store. Use Outdoor paints in red, purple orange, blue, green, yellow (whatever colors you like). The black was used to paint on the numbers and the black was to outline the numbers so they would "pop." You'll probably need more of the white than any other color. Would make a great "hop scotch" play area.