The core idea is great. It took me a bit to realise who I have to click but after that it was clear what to look for! Levels 4-10 were the real challenge after that it just got messy and I started clicking all over the place (like you said in the desc it'd be nice to have some kind of penalty system). Also level 24 took half a minute to load and 25 didn't even load, there were too many ppl for my browser to handle (it was funny) :D Also more move variety wouldn't hurt the game either.
All around interesting concept and great execution!
It's like a mixture of "Where's Waldo" and "Simon Says" :D