I liked the graphics and sounds. But in the first passage there were 2 levels in a row just with first aid kits and the boss can be killed too easily. Perhaps it is worth killing players more ruthlessly.
I also suggest that you make a game with an honest low resolution, when pixels are drawn only in a 64 by 64 grid and move discretely - from one cell to another and not between them. I hope I explained it clearly, this is a very interesting challenge.