Very cool concept! This is so far the best "time-as-HP" idea and implementation I have seen so far in this game jam.
One thing I found counterintuitive was that, when using the keyboard and mouse, aiming is still based on the character's direction. The game uses the weapon's direction to indicate that, but it is still difficult to tell. I think it won't hurt to use the mouse cursor for aiming.
The bow felt useless because many enemies won't follow the player in one line. They always offset a bit so that the horizontal arrows never hit them when the player is not moving.