Let me tell you a little something. 1) rky is right. 2) This is why, from my own experience:
The Torque engine runs a simulation of all objects on the server. This simulation handles all physics, etc. and is not managed by script. What this means is that even if it were possible to instantiate a second simulation inside the executable without crashing it (which it most likely isn't), we couldn't do it anyway because the ability to do so is not exposed to the scripting engine.
We could of course code our own engine entirely from scratch that can interact with Torque Game Engine clients. This is in fact the most viable solution, and it would take probably a good six months of work at minimum to even be working let alone stable in the right hands or god forbid stable enough for general public use, especially with the kind of morons that we get around here.
The other possible solution is something that has been made before (but not released) called BoxBuild by NiXiLL. Take your diagram that you have down there and inside the context of the 'mission' there is a theoretically infinite number of smaller 'boxes' (it creates more as needed) that players can warp between. They're moderately large (I believe something like 1024 bricks per side - that's 16 64x baseplates), have their own chat and spawning, and even a dedicated minigame within themselves (optional). That's the closest you're going to get - unfortunately NiXiLL has long since stopped playing Blockland, due to how limited the moddability really is.