This is great, not sure how the progress is going, but I could possibly help.
Hi! You should message Steven Zas, he made the original Demo and is very interested in the development of this game
Glad you contacted, I'm Gestoski, I'm the lad who went out of bounds in the original games, has ownership of the unused Zombotron vehicle game, 1st place on the Zombotron leaderboard for highscores and plenty of other things, I think Steven has other things to worry about, afterall, he passed ownership to the project, I'm not exactly sure what Darwin is doing, but I hope progress is doing alright.
Hello, I'm Steven Zas, if you're still interested after 10 months of that zombotron fangame project, I'll tell you that Darwin had a bad time with the Gestoky project, and he no longer wants to continue because when he started with Unity he had a lot of problems, user Gestoky, because he couldn't change laptops and he could never do anything, and a few days ago Darwin told me that he wants someone else to do it, so if you're interested in continuing with the project, Tom can pass it to you, since he decided to continue it after me.