It's an interesting concept as an experiment, though it takes a very uniquely talented individual to be any good at it. Many people will be very frustrated with the difficulty involved in controlling two characters simultaneously but separately, which is why most of the people playing this game will play it through as a normal game but twice, essentially. Congratulations! You've effectively doubled the time people will invest in this game without making them feel as though they're being dragged along.
Except...
The hitboxes are iffy, the controls are wood-stiff, and the playable characters fade into the background if you don't stare at them hard enough. Smooth out the control issues and brighten up your characters, and the visual side will be serviceable. The soundtrack could use some enhancement, too. Let's hear some incidental tracks instead of just an unbroken loop. I know we see a lot of comments claiming Newgrounders tend to play their own music while gaming. Give them a reason NOT to (without removing that option, of course. You never want to take away players' options a la Xbox One). Also, I keep hearing "WATCH OUT FOR SHREDDER" in the background of the loop. Who is this "Shredder"? Why should I be watching out for him? Is Shredder a "him", or am I merely projecting? Am I perhaps reading too much into this part of the audio track? Oh, look, my character just died, and we all learn a vital lesson about why unmotivated voice samples in the background loop of a game tend to drive players toward the "mute" button.
Very challenging game with a lot of promise. Most importantly, it's a very different platforming concept. Just need to iron out the... eh... technical issues.
(Okay, I really am getting tired of my computer yelling "WATCH OUT FOR SHREDDER" at me. So, at the risk of not being warned to watch out for some individual whose name or designation is "Shredder", I'm hitting the mute button myself.)