I Walk Among Zombies was pretty crazy, and I'm pissed the series is so short.
Essentially, the main selling point here is the protagonist, who is pretty damn different from the typical protagonist you find out there. For all the games who tout having a 'villainous protagonist', this game is one of the few that actually pull that off. Instead of being a roaming murderhobo, Yuusukeis a dude that looks at things logically, and doesn't hold much room in his heart for sentimentality. He's so Lawful Neutral is hurts (and makes me think he must also be somewhat autistic).
Essentially, a gift is given to the protagonist in the form of being able to walk out amongst zombies. This allows him to gather food and resources with next to zero risk.
However, even before the protagonist learns that humans can be really shitty, he pretty much states right off the bat he doesn't like them and will not go out of his way to help them unless he's given something in return. He keeps his ability hidden because he knows damn well what will happen if he reveals his secret, he will be used.
Again, this isn't a murderhobo story. Yuusuke is not above killing, but not for no reason. He claims it is a 'severe waste'. Like I said, lawful neutral.
I Walk Among Zombies highlights humanities struggle with sanity, desperation and morality in a world where the antagonist force, the zombies, are incredibly goddamn dangerous. They aren't like the Walking Dead's zombies, who shamble like they all have broken ankles and have heads that come apart as easy as paper mache. These ones are fast, more durable, and almost impossible to kill without a gun. In a world like that, how far would you go to survive? And how much would a community lean on you if you had the abilities Yuusuke did? As bad as Yuusuke is, he is FAR from the worst thing out there.
It also has some pretty fucked up surprises that Yuusuke has to deal with exclusively (revealed at the university).
So, this is the story of an opportunist trawling the zombie laden streets of the nameless town he lives in. Some of the shit he does is bad. A lot of it makes uncomfortable amounts of sense.
Plus, zombies. I honestly kinda felt like I was that kid again at some points, playing Resident Evil 2, marvelling at the burning cities and hallways choking with walking corpses.