I like the idea behind the game certainly but I think there's a few areas that could do with a little work.
First off, I personally feel the menu text's use of language is kind of hard to understand. I think the intention is to add some immersive touches to the interface for a sci-fi type setting (I think?) but it honestly just comes off as confusing. Like I thought the 'engage manual controls' button was swapping to a different control scheme or something until I clicked on it to find that it's actually the play button, and the 'operations guide' button simply shows a graphic which seems to have a pixel grid still drawn on part of it indicating the type matchups, not an actual description of how to play as I had anticipated.
I feel that in addition to the guide on the type matchups, there should be an actual list of controls. I understand that this is technically present on the launcher, but to me it doesn't feel obvious to check the input tab of the launcher because one would assume that there would be either a brief tutorial, or a controls guide within the game itself. On that note I also think it would have made more sense to either bind the weapon switching to the scrolling the scroll wheel, or to buttons above rather than below the wasd keys since these are easier to see and reach whilst playing than the default bindings which do not appear to be editable.
The second thing I'd like to bring up is that there should really be an indicator (health bars, flashing, or a sound effect perhaps?) for when you've hit an enemy successfully, when they die, and when you've absorbed them, since it was hard to tell in the present build. I think a little sound effect or a small flash of colour could work for this? The game doesn't have any sound whatsoever (I also feel that background music would be a nice addition but that's less important) but I really think there needs to be a clearer indication that you've actually dealt damage to one of the enemies.
On a more positive note the pixel graphics are nice and bright, the font/typeface for the game's text is sized well and easy to read, I quite like the enemy designs and the controls do seem to function well. Hit detection seems to have been programmed in very well which is really important for this kind of game. I think it'd be cool if there was like a little trail of smoke or light or something behind moving characters but the fact that there isn't is by no means a complaint, just something that I think would be nice and would add to the sense of movement (there's a little spray behind the enemies, but it's subtle and doesn't trail out to follow their movement). The way the player character rotates as it moves independantly of the shield's movements also looks very nice.
All in all, whilst I have largely minor critisisms, I do think this is good and that if you wanted to keep working on this, maybe figure out some controller or touchscreen support and multiple levels, this could be a really fun little arcade 'shooter' that'd work well on a fair few platforms!