I get a bang out of compulsive optimisation for whatever reason. Playing with portals, puzzling with hints... The biggest part of it all is manipulating your visleaves with func_detail. I like to keep my visleaves as square as possible, making func_detail out of even the basic shape of a room if it's not rectangular as well as any free-standing objects such as the impaled corpses outside the city. So how far do you go in it?