More or less an endless game, depends on you. There are a lot of in-game-achievements and one "big" goal, but after reaching that, the game doesn't stop, you can continue playing.Is "completing" Stardew Valley a thing, or is it just a never-ending game? Please make sure you don't give out any spoilers...
There isn’t really a clearly defined story mode, but as you progress through the game, you’ll discover more of the story and learn more about the world!Is "completing" Stardew Valley a thing, or is it just a never-ending game? Please make sure you don't give out any spoilers...



And you won't even always want the same thing. I love meeting and interacting with characters and the cutscenes, I keep trying to bring myself to run a farmer who will really be a complete social butterfly... and right now I'm running a hermit who sees other humans once a week and can barely handle doing that. And having a blast.If you go by your Task List (is this a Journal?) the game will guide you to doing a number of things so you can focus on the core tasks of the game. These are not so much a story mode as a sequential introduction to how the game is structured and how to interact with the various game mechanics. Once you get a hold of the mechanics, you will find there is a wide breadth of tasks you can do by visiting various locations and seeing what the requirements are to open or expand those locations.
As a slice-of-life game, all those things also apply to relationships you cultivate in game. The in-game characters are a key aspect for many people. But not for all! And one of the greatest aspects of the game has been mentioned by the great posts above:
You will discover what you want from the game. Which will be different from what someone else wants.
And that is GOOD.
The game is flexible enough to where you can let it hold your hand as long as you want it to, but then you release that hand to fly free and do what you wish. There are thousands of different ways to play and while the nominal end goal is opening up all the locations, you don't need to do any of that. Do the stuff you want and ignore the rest. And then do it completely the opposite next time!
Ignore 100% Perfection. I did for many years but then did it for curiousity's sake. It's nice but clearly not the point of the game, instead it's there for those who want it or who focus better with a clear final goal.
If that isn't you then that's great! This game is all about you doing what you want. So do it!