Game of the Show: Virtual Battlespace 2

Although it was first released in 2007, Virtual Battlespace 2 by Bohemia Interactive seems to be the gold standard for virtual training simulations. This is the project that is referenced most consistently across the various sessions at the I/ITSEC conference.

The nice thing about this clip is that the specific simulation features are named as you go through the video.

Given this is for the military, there's a lot of shooting going on in this clip, but there's also a good deal of general features that you'd want to see in any simulation creation engine.