Ooof, this thing is slow. I think I'd rather just be a turret than this snail-mech. And too much stuff going on! With the eye-watering channel shift and CRT effect, screenshake, huge and complicated HUD, big green things zooming across the whole screen, more big HUD arrows popping up all the time, minions wiggling around, a bunch of little dots with shadows slowly moving away from you (I know now they're people
), different colored borders on the buildings, a really fast day-night cycle for some reason, all different enemies coming at you, reticles for two different weapons that move at different speeds, dead enemies smoking garish yellow and blue . . . whew. It's just too much, both visuals and gameplay.
I do think a lot of the visual chaos could be solved by better overall art direction though, and the gameplay would probably feel a lot better if you could see what was going on. You've made a bunch of the important stuff brightly colored, which is good, but you haven't paid attention to your values(aka brightness), which is actually much more important for visibility. Look at your game in black and white:
Not the worst, you can see your minions, one of your reticles, and yourself. But you can't see the HUD at all, you can't see what parts of the landscape are solid or not, and you can barely see the enemies. The black char-marks stand out a lot even though they're totally unimportant.
And it gets worse when there's more action: can't see your own mech, minions and reticles start getting muddled with explosions and debris, and again the non-functional corpses of enemies stand out well.
Compare this to something like Alien Breed . . .
. . . which has a very clear distinction between the walls and the walkable area, bullets are extremely obvious, HUD is quite clear but also compact and out of the way so it doesn't interfere. The enemies and player are maybe not ast distinct as they could be, but they're also very different shapes than everything else, and they move around, etc.
So, I would make a list of each major element in the game, and prioritize it by how important it is for the player to see each thing. Then adjust the contrast of each element until the critila stuff is always clear, and the less important stuff doesn't distract.
I did a quick photoshop job on a screenshot to show some of what I mean. It's not great, there's more I would change, but I think it's better than the original.