At this point, it's in a Schrodinger's-type situation. It either can be in development (at a glacial pace, mind you) or not, and we would not even know unless Zeta does another public blog post in the future.
Is it finished? I wouldn't say so. Is it abandoned entirely? It feels like it, not gonna lie, and Zeta's last blog post supports this, the engine is very old and buggy and whatnot. Just a hassle to even code for it.
The good news is that Chipp is working on both a new game mode for the game and also porting the game to Unity so it makes it easier to mod it. That's practically the only thing "new" coming for this game.
Take it as what you will, but I'm surprised this game lasted as long as it did. It came out in what, 2009? It's been in development hell ever since for 13 years, and I'm literally starting to see the faults it had the more I'm reading about it. It's fascinating.