Virtual realities for ESL/EFL are just beginning to be explored. You can create a world and all the creatures in it, and have them move around and interact. A VR for language learning would have to do more than shoot-em up, however.
Here's a little construction tutorial for Second Life, where EduNation is going to come into being under the wise leadership of Gavin Dudeney, with help from Graham Stanley, Vance Stevens, and other Webheads. Coordinates for EduNation are 70, 49, 23 -- Try out the informative introductory tour by sitting on the tour stool (Command-Sit).
Warning: contains some profanity towards the end.
Other cool stuff sent to me by Nicky Hockly at the Webheads' list:
• The Second Life homepage
This gives you a good overview of what SL is all about
• Getting Started With Second Life
A step by step guide to getting started in SL, from installing and
registering to learning how to move around in SL
A site for eduactors interesting is using environments like SL in
teaching and learning. The site includes a blog, a wiki, a
discussion group, and some sample SL videos
• SLED Archives
The archives from previous discussions held by educators in SL
• You Tube – Sample Second Life Videos
A selection of videos that show you clearly what life is like in SL
And there is a gamers user group at GameLearning
Hope this gets off the ground!