Go to
Deviant Art and look at pixel art that's not picture wars. Draw inspiration from those. Conglomerate art from many people will almost never be as good as what you'd get if those people each worked on their own pieces. Trying to imitate it is not going to make you a better artist, even if you're specifically trying to get better
for picture wars.
Start over at learning to draw lighting and shading. Look up photos of how basic shapes are shaded; try to duplicate them with 3-4 colors.
Don't try to do night scenes as well-lit unless they're actually somewhere well-lit. The back of that tree, for instance, should barely be distinguishable from the night sky.
Your methods of drawing light cones/circles are pretty bad. Empty sky does not behave like that unless it's filled with fog/smoke. If that sky is, it sure doesn't look it.
Stop filling a third of your pictures with single-color dirt. Just completely crop it out and your picture gets better.
Your pixel guy is no better artistically than a stick figure. That is not a gun firing pose. He's very boring.
That alien looks like something just dropped into your picture from space invaders. Its detailing doesn't fit anything else in the picture. It also looks like it's just .. sitting there, with its wings rotated 90 degrees away from standard flying position.
Your flashlight that looks like a lightsaber isn't projecting light nearly forward enough, and it seems to be held up by a blade of grass on the light beam.