Dev probably got bored and just decided to ditch it with no explaination or telling us its abandoned
Most of these devs don't know discipline.
So once their desire/motivation fades, they stop working on it.
Although that is better than some alternatives, where they decided to just chase the money and run the game into the ground, caring little for previous promises and pandering to whoever pays more using money as their motive.
Anyway, most that would have such discipline... would probably be doing more useful things with their time anyway, or making a proper game, via learning how to actually make them. (but we hear little from them until they actually have something to show).