I think it's a stretch to call it plagiarism, as I never claimed the origin of this work to come from me and me alone. I'd say it's comparable to anyone writing a fanfiction. I did mention it in the preamble for the game, but I just realized that I didn't state in the post that I took almost every asset from the original game, and will make an addendum right now.
There's also another fan game that was released in December without any issues or complaints. If the any of the developers ask me personally to take it down, I'd be happy to.