Interesting idea, but I wonder how many people actually have good enough eyesight to play this? I didn't have trouble with it, but I'm sure my color blind father would have a hard time lol. Unless you have a visual impairment (or you're playing in a bad lighting environment) then this is really easy. I think the timer can make the game more challenging, but it's too slow to to actually be a problem in its current form. You should experiment with making it a lot faster I think!
But anyways, it's a decent game; straightforward, and functional. Good job!