Since you shared it for free now, I'll share some thoughts after my playthrough.
The game was very basic, this isn't an insult or complaint, just an observation. The ducking mechanic seemed mostly irrelevant except for a couple of levels. As can be seen in the OP pic, those platforms to jump on/over do not provide cover from enemy fire. They probably should. The level in the enemy ship had platforms that were difficult to notice, blending in with the background. Maybe that was intentional, to suggest alien design the protagonist is unfamiliar with.
Despite the special medial droid treatment received at the start of the game, there are no upgrades for weaponry or health. Also, only one level seemed to have a health top up. Perhaps at a certain point, after clearing the science lab, a choice ought to be offered upgrading health or weapon power. The virus in the computer level was very sensitive, adding difficulty in an awkward way. Just a slight tap on an arrow key could overshoot the target area quite easily. I'd suggest making the maze more complex instead, with a finer degree of control for the cursor. As for the thick health bar at the bottom, it looked odd. I would make it thinner and stick it in a corner. Probably give it a percentage too, or have it change color, starting green and turning red at the lower end.
The music was pretty good, gave an appropriate vibe. Story-wise, it was solid enough I suppose, considering the length of the game. These areas had the strongest potential for expansion in my opinion. The game starts abruptly, it could begin with more of an introduction to the ship and character. The same goes for the enemy, flesh them out more. Generally, I think you have a decent basis for making something here. As suggested by someone earlier, look at other games offered both freely and for money on such sites. It will give you an idea of the competition and what is considered worth paying for. The slightly Metroid vibes I got suggest to me this game could have an action sci-fi horror element if continued with.
Overall, a simple and brief diversion, lacking some refinement and complexity but showing some promise. Keep at it and who knows what you'll end up with.