The visuals are cool and full of personality, and made me think about Hyper Light Drifter. I think you could really spice it up and make it go from good to extraordinary by adding some particles, but all in all still great!
I think the mechanics get some time to get used to, but I managed to finish the game. The only thing that I thought was very unclear was what you meant by "retaliate" -- I first thought my character was shooting at the ghosts and it was a bug, but it turns out they were trying to steal my energy -- maybe changing the retaliate visuals and sounds so that they're not almost identical to the shooting animation could help. I like how it's ultimately better to try to bring them two by two, harvest one from each, and then move onto the next group.
The audio ambience is really nice, I think the only thing worth changing about it is the activation sound for the stones, it's twice as loud as the other sounds, and it's a bit jarring.
The pause menu is a bit bugged, pressing escape once does not freeze the game, but pressing it twice does, but since that makes the UI appear, it's not really helpful -- probably forgot to reset the time.timescale here.
All in all a very stylish submission, nice job