Thank you very much for your feedback, it's interesting.
For the sound part, I completely agree with you, we didn't had time to add all sounds like SFX for the deadline :(
Like you said, I think we can improve the user experience on the skills part and the way we get them. Now you need to collect many gems of different colors in the "light part" but some of them are hidden in the dark if you loose some light area.
The indicator arrow is a nice idea + the flickering!
Thank you again.