I played the early access build and had a some of fun, it's neat!  I had some feedback which I'm hoping is planned for future versions:

• I felt the player's character took up a lot of the center screen, made tracking my targets difficult when they were to the left or lower left of me
• I wish I could hold down left click to continuously fire
• I'm looking forward to the slight zoom in you get with looking down sights.
• The enemies had a lot of life and/or my weapon was quite weak, looking forward to some stronger weapons!
• When I'm running and shooting, my character collides with my shots

Thank you for your valuable feedbacks. We will try to adjust some of the things you have noted. For the weapon, we made it so it gets stronger and faster as you collect the crystals scattered around the map. We will also try to implement some other weapons, and we have an upgrade revamp planned as well.