Probably best to ask that here...
Unknown Worlds Forums -> NS2 General Discussion
You could also discuss your Steam issues in the dedicated TOG Steam forum
The Steam Room - The Older Gamers Forums
Here we go... a playable Natural Selection 2 engine test alpha...
Natural Selection 2 News - NS2 Engine Test released!
This is the first version of the game and game engine where you can run around on a couple small maps and fire the rifle at animated dummy targets. It isn't supposed to represent gameplay for NS2 (or really, any gameplay at all!) but serves to help us test our technology to make sure we get it running smoothly on a wide variety of computers.
If anyone here gives this a run I'm sure I'm not the only one who would like to hear about it