Even though it's quite a challenging game, I do like me a little challenge. I only really struggled at the "Hold Shift" level, but figured it out eventually.
I do like your little game, it has got some decent ideas and the design is quite nice, it reminds me a bit of the old days, back when I was young. (And no, I'm not an old geezer, but I could only play games such as Pac-Man, or something like that back then, since my mother didn't allow me to play anything modern or nice looking)
So, in summary: It's a really nice, sometimes hard little game! I like it!