I really like the idea behind this game! Playing two different games at once is a really neat idea that has a lot of potential. I would've liked to see two different genres of games on the left and right, for example, a bullet hell on the left and a rhythm game on the right. All in all this is a really neat concept executed well. Nice work! :)
The huge potential in the concept your game shows off inspires me to make my own game with similar ideas. Bit props on that!