What makes a great game? Simple rules that create complex problems. With that in mind, here's one of the best flash games I've ever seen: Planarity, the point of which is just to arrange the circles so that no lines intersect. From there the possibilities are effectively endless. And bonus: it's hosted at my alma mater, Case Western Reserve Purple Monkey Dishwasher University.

The best moments in Planarity are the many sudden Necker-cube switches, those times when your perception of 'inside' and 'outside' suddenly reverse as you slide a circle into a new position. Great stuff.

(via MonkeyFilter)