Pretty cool art and overall vibe! I really liked the mech design with the bright colors and the parallax effect in the background which created a nice sense of setting. Also nice variety of weapons kept it engaging - who doesn't love a flame thrower!
My only complainy would be that being the same height as enemies made gameplay a bit tricky as most of the times I felt I couldn't jump over their shooting so it was always a matter of killing fast with no ability to dodge, which meant I would eventually die no matter what. I know this is tricky to balance as I was somewhat expecting Contra movement which wouldn't really fit the heavy mech theme.