I really like the art. I'll be the first to admit that I am not a knowledgeable programmer, so I can only say that I enjoyed the portal gun, after a little experimentation. It's a bit hard to use, and it's not just a learning curve.

Whether or not it is purposeful, about having to figure out on your own how to use it, you could incorporate this as part of the game, and make the player have to discover how to use other similar technological relics. If you were to go this route, you could make the first level more of a playground for learning about the portal, with little hints inscribed on pillars or the like

Just my thoughts! I can't critique you too hard, this game is past my level.

Really, really do like the art.

-jonnaFin