Played through a level, here are my suggestions:
I recommend making shift lock forced OFF, I can imagine many people using shift to dash as an alternative to Q, its small but its annoying to turn off.
Some gun models need some work.
As you can probably see, the top of my drum mag is sticking through the top of my gun. And only like half of the sight is visible - it almost looks like you have 2 guns in one model?
The UI needs some work in my opinion, it feels tacky and sticks out from the rest of the game.
And most importantly, you need more mechanics. Right now all you can really do is move around and shoot the boss, needing to reload every few seconds. This just isn’t very fun for long. I recommend possibly more variety in weapons, more types & more challenging enemy attacks (and remember, more damage and health does not equal more challenging), and just some more cool mechanics. possibly power ups or something?
The map is also just flat ground. It looks good visually, but not that fun for gameplay.
Onto the pros, the animations look really really good, and it seemed to run smoothly without many bugs to deal with.
In terms of advertising, I’d recommend just trying to build a community on platforms like Tiktok, Twitter, Youtube, Instagram, etc. When you have your game more polished up this will be much easier to do.
I hope that helps! and good luck twin