Something that could have only came when the internet was still mysterious in its working. But that doesn't change how philosophical and experimental it is, and beyond all focuses on emotions through an archetype that gets sidelined and turns into a unique experience. Even though it ends as a bit of a failed attempt to be Neon Genesis Evangelion this is still an amazing feat in visual media for executing something like this and not just dying in the minds of the brilliant people who made it.
Review of Serial Experiments Lain
