I think it was very fun!
The core gameplay itself is pretty fun, with the upgrades having a nice addition to reinforce it pretty well (in addition to it being a nice use of the limitation). The effects and the graphics of the game also is pretty nice to look at too. Aside from that, I don’t know if this is a design decision or not, but the player can’t walk while shooting, both introducing a risk/reward system to the shooting (shooting leaving you vulnerable to be shot at, especially by instant lasers) and severely hindering the players movement.
All in all, this is a very good game you’ve created and as the other comments have shown, this has a lot of potential going forward.