My first review, breaking this into 2 parts due to "Shelter" being a short story and music video.
Part 1 - The Music
Hats off to the international collaboration. The combined work of American DJ Porter Robinson and French DJ Madeon opens (music, not the video) with a strong FCG chord progression and transitions in to the melancholic minor chord progression of a typical ballad. The beat rolls on despite the conflicting minor chords putting the listener in the state of expectation as we wait for a reconciliation. The intro ends and we are left with the standard sound of an easy background track to a vocal telling us the story of someone leaving home. An instrumental interlude cuts the song so the visual story can progress but we return quickly to the lyrics. The story is reinforced of someone continuing forward as a silent tribute to someone who came before and reminding the listener of hope and suggests the story is not over. As the story progresses, the music steady and true keeps us hooked. The outro does not bring us any closure and I believe this is intentional.
Overall I would rate the song as good. Standing alone the music suffers from not giving the listener anything valuable. It's just more modern electronic music with a composition that is a little confusing. This music shines when brought into unison with the story being told in the anime. Musically, many ideas are started that never get to fruition. The listener is always waiting for that big moment when things come together and it never happens. The major/minor progression is constantly fighting with the constantly positive background track forcing the listener to Pay Attention To The Show. This is a brilliant (if overused) cinematic tool which drives the sense of craving we are left with. The musical story delivers the strong tones of unanswered questions that the anime will be bringing to the table.
Part 2 - The Anime
I am happy that the style of animation is not the same 90's feel of Interstellar 5555. Opening with the main character, Rin, drowning or submerged in water as an imposed dream state with dark muted colors contrasted to Rin's very bright and child furnished room sets the tone right out the door. The audience is automatically introduced to the conflict, reality vs. illusion, and left with precisely 0 clue which is which. Though Rin opens in a dream of drowning interspersed with memories of a desolate world and then awakens, the world Rin awakens to is immediately revealed as fantasy to our eyes. Quick note, Rin has not received a message in just under 7 years according to her tablet. Her isolated world of joyous child fantasy is vibrant and shows just how much innocence and fragility Rin brings to the table. When a swing appears in her day dream that she did not draw Rin is forced to remember things she would rather not confront. Memories of a world before, and the only other human character in the short, her father, flood her world in spite of her intent. Rin is drug down (literally) to despair and pain as she realizes she was once not alone. The exit scene leaves the audience exactly where they expected, afloat in space. Rin is now 14 and drifting endlessly towards, according to fan theories and the ship display, Mars.
So, this is tough. My take away from this short story is not about a science fiction post apocalyptic setting. My conclusion is based on the lack of other people present. I understand the last human alive premise but there are no other people in memory, either. Given that there are exactly 2 people in the story, that's what I think it's about. The story of a fragile girl who lost her dad. She is lost in her world that does not change. She is, also, in constant battle to determine reality from imagination. Even as she says she is not sad that she has these painful memories and smiles inside her dream, her real body cries. This is a story about pain, and about how we try to deal with it. There isn't a clear answer if the ending is good or bad, to me. It's open enough that the viewer can choose.