Amazing game with sick graphics and very cool guns! Looks like a really well-made product, very professional.
I think that the game itself is in most of its aspects really fun, but I think you should spice it a bit up to make it more fun and addictive! I would LOVE a 2-player mode where you can also move around the area and get different weapons and so on, that would be neat
Also, more possibilities to fight, except for just simultaneously switching between left click and right click would maybe be having the player to aim with both characters at the same time and also be able to shoot at flying enemies and so on
Ok, that was my quick review for this game. Hope you'll add some points that I mentioned to the game sometime or later ^^