Earth game/simulation

The company I'm working for wants to attempt to create an Earth game/simulation (serious game). We'd like this to run both autonomously and also with (possibly many) people controlling different entities like people, cars, airplanes, etc. (similar to MMORPG). That's the gist of it. But, here is a listing of the main requirements.

1. Support for DTED data (terrain) importing. I see that Torque3D supports GIS data, but does it at a global level? An old forum post (2007?) seemed to say this wasn't supported. We'd also like to zoom in/out on the Earth (all the way out to space) to view from a top level. This is very similar to Google Earth. Visual3D.NET provides this support--see video for example at http://vimeo.com/27905417.
2. Simulation playback/rewind. After running a simulation, whether with a human in the loop or not, we'll want to replay it (faster/slower) to better understand the simulation run.
3. Scalability -- We're talking about a lot of entities that will require a lot of CPU so we'll need good scalability. Each entity will also has to store it's state as it goes for later playback (#2)

There are others but these are the biggies. Thanks for any info/tips you can give.