So design a “game” with no goals =/
I hardly think this has to be designed. Drop a person into the middle of an unknown city and let the world be their “toy”.
But you’re probably looking for something alot more …. plausible.
Actually for some reason all i keep thinking of is like little lab experiments with mice. Where you put them inside a maze and see what happens.
Anyway…. how about, a digital play room, where using your hand or something you can draw objects onto the screen, once finished the object now exists in your “play-space”. The “play-space” is essentially a screen, a lit background behind the interactor projects a shadow of themselves which is what the players use to interact within the play-space.
Now if we introduce a few more little interesting dynamics like the ability to scale shadows (have a little man running along a normal sized person’s arm?) or turn off gravity? Or even random modifications to a person’s shadow. It could provide the basics for a very interesting and fun playing area.