Graphics and sound effects are nice. Messing around with gun modifiers was fun, although as other have pointed out, the UI could use a little work.
I'm not sure if this is intended to be a browser game, or if it just happens to run in a browser, but when I tried to use the scroll wheel to switch guns, the page scrolled downwards. If I went into fullscreen, it only took up about a quarter of my monitor (my resolution is 3840x2160). Also, when I tried to drag a modifier into space, my browser interpreted that as me trying to click and drag a link. It opened a page with just "null" in the URL bar.