Yandere Simulator is a game about a Japanese schoolgirl killing other Japanese schoolgirls. It's a school sandbox setting, like Bully, but this game looks at a very particular brand of bullying.
The act of stalking, killing, and then hiding a body is so passe in gaming these days it wouldn't even get funding without an additional hook. Mechanically, Yandere Simulator is no different to that, though it's almost impossible these days to get a game rated in which you're killing children. Think back on all your time in GTA -- were there any kids on the street to run over? In this game, however, you are a schoolgirl as well. So, it's a kid murdering kids. Which has News in a bit of a tizzy.
What really sets Yandere Simulator apart is the additional torture you can inflict in-between all of that -- keep someone locked in a closet if you want to, and torture them, break them psychologically, and get them to do your bidding before committing suicide.
That's not necessary, though. The main goal of the game is to get other girls to stop talking to your boyfriend, by any means necessary. That could just mean incentivising them to stay home, or getting them expelled. You play a jealous girl with serious problems, and while the path of least resistance probably doesn't always involve murder, sometimes you might need to make an example.
Before you say "Oh, those Japanese," this game is actually made by a Californian. Though it is sort of meant to be a look at a more extreme, caricatured version of Japanese schoolgirl bullying. It's going for shock value, for sure - it is a horror game, after all - but there does seem to be more to this one than, say, Hatred.
According to the creator's comments to Vice, the game might actually have points within about the known practice of schoolgirls spending time with older men for money.
While the developer says the game is only 5% complete and doesn't have any objectives or win condition yet, a testing build is available on the downloads section of its site which you can play right now.