It would have been nice if the green cube could jump off the wall it's stuck to. I'm not sure if you intended that to happen.
Ideally, the jumping would be variably timed. Not being able to let go of the jump input for a short jump doesn't feel good when jumping between platforms near each other.
I could rarely see where I was going. If the camera must be zoomed in so much then the ability to hold down or up and have the camera pan in that direction to give you a glimpse at whats there would have been nice. It's a common feature in platforming games to account for anytime the player can't see where they're going.
"W" for jumping is very inconsistent with platformer games or just games in general. It felt very weird to have to relearn the muscle memory for such a basic control; spacebar would have been nice. The music is very loud. I'd recommend adding a volume slider, a mute button, or making the music audio file just plain quieter.
The music fits nicely with the vibe of the game (nice choice). The character art is basic but still neat in its own way; and it fits with the background art reasonably well. The main gameplay idea is a good one. It feels fairly smooth to switch between characters (I like the "tab" key for that).
Overall a nice entry.