Playground Maker: The World is Now a Playground
Using Second Surface, one can create playgrounds for others to play in the real world. Only doodles for boundaries are needed to create levels.
walls (thick lines) that can be adjusted
boxes and circles that can be scaled
add rules to the game, perhaps just writing a doodle at the start is enough
colors, rules can define what they do: green for good, red for bad, etc.