aww...
I'm going to be honest i've got a nerdy boner to this just because of the thought that it all onscreen may be done completely on your own. Quite possibly because i'm onto creating my own renderer system right now, so everything that might fall into the same category is highly interesting for me at the moment
But still, i've tried out your demo, and really liked it. Too bad nothing indicated the switch is going to be the end of the level, when i first saw the blue keycard next to a blue door, i immediately ran back to the first blue door i saw to try and see what's hidden there first, and baaam, game finished!
I think you've settled with just the right graphics style, don't really mess with that one or you may risk losing a fan here