Hello! Welcome to Feedback Quest 5! It's nice to meet you! My name's Hythrain. I'm part of the FQ team and a hobbystreamer. I'm writing this review live after having played your game.
The concept for this is quite interesting to me, though there are certainly aspects that felt awkward to do.
I'm going to begin by echoing the idea that the controls for shooting should be mouse based while using WASD for movement. I'm also going to go further and say that the mouse cursor should be used for aiming the first shot, because a lot of times a straight shot isn't good for a starting shot. This is especially true when ships begin moving on curves.
Beyond this, I want to talk about the gameplay itself. The idea of a shot you have to send back and forth is interesting, but I find that the complexity to do this efficiently is hindered by... well, too much going on. You have ships that shoot, ships that can deflect the shot, and ships that explode in eight directions when destroyed. All of these things can make it more difficult to get the right shots lined up. Now I'm not saying difficulty is a bad thing, but I would imagine if you tried to scale the difficulty up higher than it is now you'd end up with something that is too challenging. I'd recommend slowing down the speed of waves and giving players an easier time to kill enemies. For example, I would say that the ships that explode on death shouldn't be combined with ships that are shooting at the player. This can get a bit overwhelming, especially at higher difficulties. Instead, I'd say you should make a variety of enemy types beyond what you have and see which combinations offer the right balance (the shield enemies and exploding enemies work well together, for example). Finally, I'd say the laser should just be able spamming it in a set duration instead of a limited number of shots, since there are times where the arrangement of enemies just won't be nice and the player can't always predict when those good times will come.
One idea that I just had that I want to suggest: once the player fires the shot, they have to hit a specific input for it to actually return. That way, if the player wants to shoot a certain way and not have to move, the shot will just travel through them. This could help alleviate some difficulty from above, since now they don't need to always be moving.
I do love the concept, though, and I'd love to see it improved.