Okay, my brain is swimming in too much information right now... I wanted to post something about this bit of research, but I've still got a lot of reading to do before a solid, discussable perspective coagulates. For now, you might just want to start some research alongside mine and see where it takes you. I'll talk more about what I'm seeing later. Here's the deal real quick:

Garage Games has announced that their Constructor project has hit the beta phase. Torque Constructor is a ".map (as in the .map file format) editing and .dif (the Torque interior file format) producing program" for creating 3D content for the Torque 3D engine. It might also work for creating content for anything that uses .map, but I'm not sure yet -- like I said, I'm still underway on this voyage. If you've been using Valve's Hammer, GtkRadiant or maybe QuArK to do some level editing, you might be right on board, too... if you don't know what any of those are, you have more research to do! :P

If that's enough to pique your interest, you really ought to shoot over and start reading. Great stuff! There's a great batch of links on that post that will get you well on the way to understanding more about Constructor.

Also, that blog post serves as a fantastic introduction to concave vs. convex models, specifically how they are treated in Torque, but it's a great read for any 3D game artist, I think.