There are many things that I wanted to add but couldn't, such as giving the line some area collision so I could add enemies. That was my idea behind the turret station, but I couldn't get the area collision working, so I just added some breakable tiles.
So yeah, maybe I'll continue working on this in the future. I learned a lot of things while making this one, so maybe I'll make the game from scratch again and continue where I finished it.