some work needed
'givin' you 8 for the principle, as that game is quite close to perfection. the only things you need is:
gameplay: make the mechs move faster, allow doging (that means bullet sprites for all weapons) and give more type of weps. and tools.
lower robot health or increase firepower. people HATE to stay on a chair watching bullets move for half an hour
art/graphics: try to look at mechas art in google, it should get you started. mechas would surrely go on tracks, but NOT on thrusters.
sound: a tick you could do is remove sound at first, put all the game ad-ons and do the sounds at last. screw the music, it takes a lot of work and memory, work moar on the graphics, it's much more important.
i saw that it is your "1.0" version, so i expect you will add improvement, and am looking towards it.
good luck, even though you might not need it. you've got the skills required, and maybe the gas too :))