Ok, so this is a cool idea. The downfall is that it doesn't work great. Accidentally selecting the wrong thing occurs so often that the game is not really playable (at least for me). I think it would be a cool simple game, but since it's so difficult to select what you are actually trying to select the game is just frustrating.
Overall, I think it needs improvement.
I don't see webcam games that often, so I give you points for innovation :)
Now, the detection was not the best, even against a white background. Still, I enjoyed playing it a few rounds, so congrats ;)