Ah. Indoor. That's a good question! I really haven't thought about that. Right now, I've implemented various collision detection stuff for objects. Like, trees are cylinders, static buildings are boxes. I also implemented a "full" collision detection system, where I've tested a 500-poly church (the one in the images), so you can run inside, collide with walls and ceiling and such. However, "large" indoor buildings will *not yet* be implemented, that is, portal-based BSP levels and so on. At least not for the upcoming version.
Alas, in the beginning I'll only be focusing on outdoor scenarios, scattered with small houses, caves and such inserted by the user, without any space partitioning of these. And then we'll see what happens =)
Right now I'm working on user-friendliness. I am not a particularly user-friendly guy right now, because I have to create listboxes and buttons and labels and blah need find good ways of presenting the stuff. And at the same time fix bugs, bugs, soon implement a dropdown-list-fontex-object, fix more bugs, all while I should be producing cosmological PhD-work =)
Last week I even brought Polly to bed, which upset my girlfriend more than usual.