Here's a question. If you found a virtual world in a video game, would you think much of what you did in it? What if you found a computer in the virtual world? What if that computer ran like an actual computer and you were able to get X up and run OpenOffice.org?
I wonder, really I do, about the implications of a computer game that would spawn computers inside it using, say, a hypervisor on a cluster utulizing special virtual CDs found in the game world that were really scripts to install the basic system to the virtual machine. Really I do.
Obviously whoever has access to the machine can monitor you, track your progress, keep tabs on the state of secure handshakes using modified software made to leak, and compromise any security you can conceive; you don't want to rely on a public server to secure your stuff because you have encrypted disk and connection. But what about private applications, or testing? What could you conceivably do, really, with this?
Let's say the game engine is smart enough to have Xen balance out its individual computers across a flexible cluster that can be grown and shrunk without down time, by adding and removing nodes (i.e. physical computers). Existing nodes being removed evacuate to the network; they can then be massively upgraded and plugged back in, at which point the network makes them a supporting node and adds the added hardware to its own. This is relatively normal for a cluster; but the control by a game engine isn't.
So let's say the cluster, controlled by the "game," is pretending to be a network now. You can configure networking in the game by walking up to a computer and looking at an X screen exported out to the game, or a console supplied by Xen and filtered through the game. Hit the console, configure the network. The back-end work to make the computer act physically connected is handled by the game engine; if you run physical cables, the game tells Xen to pretend these computers are bridged.
You now have a "game" in which you can pretend to build a network; set up servers; and run cabling. The only thing you can't do is simulate hardware failure; and tweaking it to use a few real machines that you obviously have to hack up in the real world will fix that. Using a mixed environment, you can have multiple clusters of PPC, x86-64, and IA-32 architecture, each acting as a cluster with all the others of its architecture, with the three clusters acting as individual from one another instead of doing something stupid like trying to share processes across eachother.
Taking this a step further, a kernel with Xen in it can run on any of these machines. The game understands when they reboot, and tells Xen to restart them. You can mess with them and patch them and upgrade them and throw security enhancements like GrSecurity on them if you can make Xen not barf with them. You can set up secure nodes and run them and test them, quite literally, in a sort of "half-simulated" environment.
At the end of the day, of course, you could shoot your boss in the forehead on the way out of the "office;" he'll just respawn with the BFG.