Although the game fits the theme very well, it lacks something to make it interesting. The game seems very slow and floaty and monotonous. I didn't ever feel the need to use anything but the basic gun, mostly I was using the other things to prevent getting bored.
I think the game could work as a base for something better, some extra work could turn it into something quite enjoyable. If you want to continue this game anytime in the future, consider starting by making the movement of everything faster and the player smaller.