I loved to play this! It's very simple, yet so much fun when you understand how it works! The idea is original, and it makes it more original because you took one of the most simple games ever created and added some challenge to it!
Although the main menu's instruction helps with understanding the concept of the game, I feel like it might not reach everyone right away. It didn't with me but I was interested and curious enough to stay and understand how it worked. Other people might not and might drop it almost as fast as they clicked it! Maybe a simple instructional/exemplifying screen will suffice! Anyway, that doesn't take anything from how original and fun the concept is!
I like how you only used palettes of two colors, it's simple but still appealing, so are the animations scattered around the game! Although I couldn't help but feel like the rounds I played were going by a little too fast. In the end of every round, it told me who won, but it didn't give me any time to grasp the how's and why's of it, sending me off to the next game right away. Like mentioned by someone else, the audio (and the game, in general) lacks Gameboy-ness, although it's still enjoyable and adds to the game!
All in all, this is a pretty interesting and fun game, so congratulations for that!! :)