This is the lesser-known companion Playstation game to the classic anime Serial Experiments Lain. There's a downloadable version as well. The bottom of this page has the chart of keyboard controls.
Also, the gameplay is highly unconventional. It's not like a regular visual novel. It has a totally different style and purpose and interface than Disco Elysium, but it takes the same sort of patience and open mindedness.
How closely does it tie in to the anime?
haven't played the game (it was basically impossible to find translated versions until now) but from what I heard it has the same general plot but the details are different, and it had a darker tone than the show
I think it's a separate continuity
Exactly right. It's another experiment in the series.