I would make it more obvious in game what you're supposed to do. Also include some text when infront of an object you can interact with, because I had to press random buttons until something happened.
One of the first things I noticed was the settings/how to play button doesn't do anything.
I like the static effect over the screen :), but the environment being entirely Grey, I wasn't sure where I'm supposed to be/go or what I'm supposed to do.
I would give the player some hints towards where more collectables are and maybe make the maze easier to navigate. I found it hard to navigate since it all looked the same and because of this it took me a while to find the enemy you mentioned, and it ran away from me. I never did find any more green collectibles so I would add more of them and make it more clear what the player is supposed to do, and make the grain/static on the screen more obvious if the player is going in the right direction.
Overall it's pretty good but I would try and add more stuff to make it more interesting and obvious about what to do! :)
