Game development is always a time-consuming and long process.
When the game gets bigger, the game also needs more time.
But you can always do ( Make some small improvements and make a small continuation of the plot and in the next update, for example, make more of the plot) You can just try to alternate one with the other yes, maybe it will be small pieces, but every month.
Do not forget that improvements are not always made, but only sometimes. And these improvements are needed for the game and the plot of the game. As soon as the improvements are made, the continuation of the plot will begin
Or do not complain and get more improvements and continuations, but wait longer.
What kind of pessimism (OH, there is not enough plot) For most authors in the same way

yes, it's unpleasant, but this is the development of the game, it was not and will not be simple (Many updates are not big. And almost everyone has the same complaints. (OH, there is not enough plot, oh, the author just milks his sponsors) and there are complaints under each game and the complaints themselves are the same).
Only those who do not give up and continue to do their job reach completion. (I'm talking about the normal completion of the game and not about those where the games in the middle get some kind of ending

)
There is no need to put so much pressure on the author.
Otherwise, we will get an empty and unfinished world of the game.
To make the game more interesting, the game world needs good content !