A Great Start
I really enjoyed the demo. The use of 3D environments and screen panning is a great idea, it really fits this puzzle style game. I look forward to the completion of it.
I think it would benefit from more challanging puzzles (perhaps you were planning this the further you went in the game?). Also, the zombie sequences need vast improvment, its almost less than a point and click since its only limited to the X-axis, you can't move the cursor up and down, making it really, really easy to take out the zombies. If the zombie attack had more urgency, perhaps a better aiming system (both X axis and Y axis) it would be more enjoyable.
Overall great job so far. Good luck with the continuing development of the game.