In true fashion that Lain herself would approve of, no less: exclusively via the Wired.
This effort is nothing short of astonishing. The team remade the game from the ground up, then hardcoded subs to translate what was thought to be an untranslatable game due to the biblical scope of what’s an exclusively voice acted experience.
Serial Experiments Lain was developed concurrently with the series, and designed to be its own thing, though you could probably make a case to tie it into the show, if you wanted.
It’s not so much a game as it is an A/V experience. You explore diary entries, listen to interviews between Lain and her psychologist, and spiral further down the rabbit hole until you learn the truth: both literally and figuratively.
If you’re even a cursory fan of the series, or a hardcore obsessee like yours truly, it is a must-play.