I really like this, so I'll critizise on a high level:
The screen effect when I failed to destroy a time orb was cool, but FAR to long in my opinion so it got really annoying, 1-2 seconds would be better I think.
The aiming changes the arm rotation directly, am I right? when walking normally, it worked fine, but a soon as the body tumbled in slow motion it felt very wonky and inaccurate. I would have liked it more if the control input affected a centered crosshair and if the arm automatically moved to aim towards that point - as a result I never really wanted to use the slow motion - the added difficulty for aiming punishes me for trying to pull of cool moves.
I didn't like that falling of an edge also triggers slow motion.
Enemies spawning very close to the player is unfair, my suggestion to lower the frustration is: to spawn everything outside of a certain radius from the player, but give them a temporary boost in movement speed to catch up, or: to spawn them with a delayed start, so players can move away even if enemies spawn surrounding them.
I would also like the ability to jump forwards and backwards with slow motion.
In my opinion you have a very good prototype to build on and create something truly fun, I would like to see it being developed into a polished game. Well done! :)