The dev has, I believe, said that they aren't going to update this game anymore. I think it was because the lead developer left.
It is indeed quite sad. However, there is someone on the Discord working on a mod for the game that would add a lot more 'mons, that is if the scope is fully reached, as well as a fishing minigame and maybe even Legendaries as a "stretch goal" of sorts. Go check that out if you're interested. Nowhere near completion as of yet, but it's still quite interesting to see the development process.