Out today, That Dragon, Cancer is a game about the slow, painful, and confusing death of the author’s son by way of a rare cancer.
It tells its story through a series of vignette levels; in each, you have restricted navigational options to explore a 3D space, while audio and in-world manifestations of text fill in what is going on in the family at this point. Often you can hear the conversations of people whom you cannot see, which gives the sense of a ghostly dissociation.
The mechanics vary: sometimes you’re there only to look at a set number of things before triggering an advancement; elsewhere, you actually need to complete some small task, such as running a not-too-difficult platformer. Sometimes you need to spend a certain amount of time in a space with a screaming child in pain, and not be able to do anything about it. This is not a remotely pleasant or play-like experience, which of course is the point. But I often did feel that I was being offered an experience I haven’t seen anywhere else in games.
Emily Short's Interactive Storytelling 