Really interesting concept. I feel that the game could do with a bit more of a challenge.
Did you consider a more "rhythmic" input scheme, such as the one in QWOP? Something along the lines of alternative between keypresses would really add to the sense of tension that the game cover image seems to convey. The current scheme could be left in as an accessibility option.
PS: Great job on the cover image! We've always resorted to putting in a screenshot of the game as a cover image instead of creating new art for it :D