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Stardew Valley is based on existing formula but it is incredibly polished and even people not from this genre play(ed) it. It has something special, similar games don't.
However I think that quality trumps for indie games. There are always exceptions and some "shit" games are hyped because of some Twitch or Youtube coverage. And of course there are some (maybe many?) games that have a high quality and fail. You don't just need quality. But you need it. And you obviously can make a good game in a bad time.
As for the game in the article. I don't want to disparage the author because making a game of this scope is incredible!
However watching a video on his game's site instantly gave me two reasons why the game is not successful.
- The movement of the character looks very stiff and unnatural. - It is missing atmosphere. A lot of repeating textures. No details which makes the whole world uninspiring and uninteresting.
Now these things can be changed and improved still. But in the end the market for this specific type of game really is a hard one. And you compete with game's made by bigger teams and bigger budgets.