About the mechanic being copied, you're probably right. About the level being assembled from several assets, also (but what is a level, if not something made out of assets ? Not sure about your point here haha). And the pixel shader, already made in Unity, right too. But, please keep in mind that I made all of this alone (despite the music), and I'm not saying this as an excuse, but making a game alone is hard, especially for motivation, so I simply prefered making a simple game but well polished and work on juiciness a lot, that try to create a new mechanic, because I'm a programmer more than a game designer.
I hope you can get my point, and I'm sorry if you're bothered by the fact that people are enjoying the game, though I'm not sure what I can do about it...
Thanks for taking the time to share your thought!