I will only touch on the flaws as others have covered it before. The overheating is irritating. While it does train you to fire in bursts, you don't have enough damage output that way to survive for long. I agree that the balance needs work. Either adjust the overheat mechanic, add power ups or something. I would suggest after dying clear the board on respawn to prevent from getting overwhelmed. Also the short, squat robots were a bit of a pain because I was reliant on the bullets going on a downward angle to get them, perhaps adjust their hitbox a little so the straight forward shots also connect and the upward angled ones miss?
I did like some of the little touches, like firing moves you back slightly.
The music was nice and low rez fitting the pixely nature of hte graphics. It did remind me of the classic run and gun games like Contra.
I would normally give 4 stars for this (3 for raw game, half for the music and another half for how well it goes together), but given this is your very 1st submission, I'll grade on a curve and go 4.5.
Not a flawless product, but a great start.
Keep up the good work!