I like this game! Too bad there are so few levels in the demo...

I could have played more. BTW, maybe you'd rather stop the game with a nag screen after the last demo level has been beaten instead of replaying it forever.
I generaly agree with what the others have said. The default window size is too small to read the text and see the devices, but when maximized (in 1024x768) it's ok. So my advice would be, just open the window maximized! That way you don't get the disadvantages of full screen (moving desktop icons, reboot needed in case of freeze/crash, things messing up when the firewall window opens...).
I also think the game should be playable with the arrow keys, at least in one player mode.
The tutorial was difficult to understand, especially since there are several things to read/look at at the same time.
But overall, I think it's a pretty nice idea done well, and I like having to understand how to build the machines so that they fly/roll/don't crash to the other side.