I know this is just a demo project, but I thought the game was broken at first, since the portal gun didn't seem to do anything. It isn't until the third level that you can actually use the portal gun, and then you can only use it on the non-boundary lines (as in, you can't use the ceiling or the walls).
I figured it was broken (on my browser) too, and I didn't know how to get to other levels. After seeing your comment I went back and saw that touching the rectangle with the yellow glow takes me to the next level. (On the first level this requires a jump, which is done with the up-arrow key.)
