no, you can't access the higher levels, although i'm considering giving it a lower level accesible through ramps, but come to think of it, i think that would make it too big. i'm going to scale down the whole thing too, to make it just a little quicker to get from base to base. and of course it needs more detail; i just booleaned several cylinders to thest the overall layout. when i get around to it i'm going to add some pillars as cover in the middle- is that what you mean? also i'm going to add a dip in the middle of the outermost cylinder, and add a bit more area and cover to the bases, and some nooks here and there.