Harder, but with what purpose?
I like the idea, but honestly, I felt like you were trying to make the game more interesting with the crazy screen movement. For me, it was a bit like telling me that I'm going to have more challenging fun on my Wii today because I'm going to cover one eye. No, it will be more challenging, but a challenge that doesn't relate to game play ultimately (in my experience) just becomes tedious or annoying. I think version 2.0 should bag all the screen "tricks" and introduce more challenges that relate to the game. Obstacles, enemy size, enemy fire, hyperspaces, etc. are all ways people have worked to make their game get bigger and more interesting -- and challenging -- as game play progresses. I think you'll have a lot better player retention if you get a good cup of coffee and try to brainstorm what people haven't yet done with this kind of game that you can incorporate. There's another series of games out there that have the same limitation (IMHO), where you have to hold down a different keyboard key before shooting so that your bullets will be the right color for the target. In the same way this is similar to me--that's just complication, not challenge.
Otherwise, I liked all other game elements... playability, firing, movement, art.