Not exactly the most novel of concepts, but decent execution. Adding the timer element was a nice touch, though I wish it had been relevant a little more, I only ever really had to consider it in the final level. Also wish you had told me about the suicide button earlier. The final puzzle was nice, but at least for me it broke the rule of thumb that once a puzzle is solved, execution should be relatively simple -- maybe adding another checkpoint here would have been nice? Still, overall, a solid little entry, well done!