This demo is the Cube level from Zof.
You will find puzzlement, exasperation and elation in the same proportions as in the actual game. So it's probably a good guide.
It's quite a simple level, once you get what's going on. People are pretty much split down the middle on this. Half of them get it in 10 minutes, the other half spend a long time here. Which also good.
There are two main hurdles. One is realizing what information is being given to you ( what's the little cube 'saying' ). The other, is realizing what assumption you have made, which is not true ( about teleporters ).
You can use the guide in the community section if you get really stuck.