Really interesting concept. I so wanna play this co-op with a friend. As a one player game I had some issues.
I got disoriented in terms of which of the orbs were controlled by which control scheme and ended up dying a lot of times by untethering and going in opposite direction. Maybe some indicator by color.
I don't feel the tether... or any resistance between the bond like i'd anticipated so it's difficult to know when i'd break it.
May be a bug... but if an orb touches a wall sometimes the tether breaks even with the slightest of collisions detected.
The primary challenge for me was to get familiar with the control schemes. After which the game is really satisfying. :)