Impressive how you managed to make a run and gun that works so smooth and has a lot of personality with these restrictions (and so little time too). As someone else pointed out in the comments, there's some little issue with the readability (the soldiers arms and the turrets sometimes blend in with the background, especially when they're at the top of the screen, where also the bullets tend to be less visible cause of the flames), but it's a small thing (that can be easily fixed modifying the palette a bit, i guess).
Kudos!