On the surface, this feels like a Harvest Moon clone; a simulation game in which you build a farm and make friends with the villagers. And while that's accurate, there's a ton of depth to it. In addition to farming an assortment of plants and raising various animals, you can also fish, forage, mine, cook, forge and craft. And there are action-rpg areas where you can fight monsters! There's a sidequest area where you can unlock new areas or crafts by collecting various items (...which is really the “main quest” to the extent there is one); there are daily quests for the villagers that earn their affection (and you can also give them gifts); and there are plot-events that happen in certain areas at certain times.
And you can generally ignore anything you dislike. If you get tired of farming or hate the fishing minigame, you can do pretty well without them. (Assuming you consider “earn money and build up the farm” to be the primary goal.) I actually ignored most of the social aspects and virtually all decorating in favor of building my farm. The game allows you to attract a spouse (of either gender; they all appear romance-able regardless of the gender of your main character) and have children, which I didn't bother with.
The fact that your character doesn't seem to need food/water/warmth is actually a major selling point to me, because it means penalties for failure are less and death-spirals are much less likely. Eating restores your endurance and lets you do more things in a day, but if you never eat, you suffer no ill effects. If you run out of endurance (or stay up past 2am) or run out of health in the mine, you're charged for hauling you back to bed and you might lose some items, but there are no long-term penalties. If you don't feed your animals, they stop producing milk or eggs, but just start feeding them again and all will be well. If the developer eventually feels this needs more “realism” and thinks, “Maybe working in the rain should carry risk of getting sick, or the summer sun should cost more endurance,” my advice is: Nope! It doesn't need to be realistic, it needs to be a good game.
I think the major turning point in my finances—which came very early—was when I figured out mayonnaise. You can construct a mayo maker and put eggs in it, and it effectively doubles their sell price. And you can do it multiple times a day. Once you have two chickens and a mayo maker, you have the ready cash for most other things. I also basically cleared out the mine before the second year and didn't build a barn until then, which meant I didn't have to worry about getting home at 6pm to close my barn doors while I was spelunking.
I considered the game “completed” when I finish the community center quest and got the trophy. In theory you get a score ranking after 3 years, but I'd already grown and shipping almost all the crops, beaten the dungeon, unlocked the hidden areas, etc. I could spend another 40 hours becoming a millionaire, getting married, finding all the secrets and getting every achievement; but I think I've had my fun and am ready to be finished.
Overall: The game has amazing “flow” and the “just one more day” impulse is strong. The potential for addiction is very high. I quite enjoyed it, and recommend it with caution.