You've done a great job, my fave part is the gun, but there's something not quite right with the composition, because it feels overcrowded/cramped. What I suggest is that you clear up the part underneath the gun (those random tentacles), and perhaps move the line of aliens further to the right, like coming from the top right corner, and maybe lower and center the gun a bit more, like it's squashing the aliens in the corner, whereas the character is confident and at ease, stretching out his arm, gun held. Hope my feedback's helpful.