The 'Half - Life' series is known for its immersive gameplay. It follows the adventures of Gordon Freeman. He's a scientist who finds himself in the middle of a lot of chaos at the Black Mesa Research Facility. There are strange alien creatures and all sorts of dangerous situations. He has to fight his way through using a variety of weapons, and the story is filled with mystery and action.
I'm not sure specifically as I haven't read it. It could be about a person's internal struggle where they feel like there are two parts of themselves, and the story might revolve around exploring one of those parts, like half of their personality, half of their desires, or half of their identity.