Looking very good RE! Been meddling with pure-ISO and visibility lately as well a bit. It's kinda hard with muti-levels, and my way is still to layout the dungeon in a way that I have no (or almost no) overlap between levels (which reduces layout-out possibilities dramatically of course ). As for walls and visibility I think you're on the right track. The wireframes of the arches look pretty cool this way. Maybe you can use some glass material to show them with some opacity in sketchup (never worked with glass materials myself though). Getting good shades is also hard using sketchup. Normally you'd have small, multiple lightsources in a dungeon. Currently your shades are very long, maybe you could get the lightsource up higher to increase the effect of a dungeon with ceilings... (I think sketchup does not support multiple lightsources but Im not sure) or maybe post-process shades in PS (would look the best I guess but also would take a lot of time ) Also maybe possible to load the model in another 3d-tool and add light sources. Also actual rendering in sketchup is pretty bad so using another finishing tool may be a way (I know architects use sketch-up a lot for mockups and then load this in 'real' modellers to do the rendering)..... well, just my thoughts... cheers!