I wish I could leave a mixed review instead and this game looked promising, but... I love exploration or walking simulator games, but there are little to no substance other than a few empty corridors, a huge open space and "Hey, here's a level that looks like it's from Super Mario 64!" Really... if you're going to go for an exploration game, encourage and reward people for it and don't just let people walk through a linear corridor where there is nothing to enjoy and do besides looking for an exit to the next level. The pleasing visual style you coat the game with won't help the game at all.

Moreover... for a platformer game, it's pretty basic and easy but most of the game are just empty mazes which serves no purpose to the game (ehem, game-length padding). This game feels more like a glorified demo. Other than that the story is alright, but that's about it. Shrugs for No-Face Wannabe. [6/10]

To try and conjure up a less pedestrian review, OYASUMII struck me as a game people may struggle to understand lest they make a conscious effort to worm themselves into the mind of the people behind it -- the game itself functioning as a dive into a variety of interiors inspired by various IPs of a timeless era, even taking numerous inspirations points across its canvas that it proudly wears.

What this game felt like me, with all of what little narrative pieces it has to string together some kind of a story to try and ground, to try and explain the existence of its moving parts felt meaningless once the very first train segment hit. This game is essentially made by a dreamer themselves, with each of the games traversal segments that're more exacerbated and set-dressed to act as fragments of ones nostalgia, which the main conflict of the game makes known it desires for the player to understand that one can either make an effort to stay entrapped by ones nostalgia, ones past, or do what they can to move forward and allow the past to propel them forwards into the future.

The 'golden-age' gaming references were all rather expected, some a little cuter than others. The games 'good' ending was maybe a little *too* on the nose but the sentiment of how all of these things impacted the person writing the game, envisioning how they'd extrapolate from their own experiences and memories, to paint a certain picture with a full studio aiding them, to me at least, was fully understood. I see this game as someone wanting imagery, wanting art and the like to describe how it feels to get lost in nostalgia, and if one were able to physically inhabit or wander the past, how empty and how daunting it might feel for the magic is gone -- the feelings un-similar to when you were once an adolescent.

Short, inexpensive, visually striking, and rather charming, with a very colorful musical arrangement. I really liked this experience!

A lot of people talk about this being like Yume Nikki or other walking simulators, but it really seems to be doing something different. I enjoyed playing it for what it's worth, but it's a bit of an odd mishmash.
It's got atmosphere, that varies from light and airy to rumbling and oppressive. It alternates between good 3D platforming and tension-building exploration sparsely sprinkled with jumpscares.
The environments are the main character in games like these, and they range from what I assume to be original, light-hearted, open, and creative, to small, referential (there are quite a few levels later on that are sections of Mario 64), empty, and foreboding.
Me personally I'm not a big horror fan, so I really wanted more of the light-hearted areas, and the platforming had a good feel to it. To the point I was thinking to myself that they would have spent their time better just building an unabashed 3D platformer.
There's some plot going on, and honestly it isn't hard to follow per-se, but it's a little barebones, with so few kernels of info to connect together that who is to say what it exactly means other than the general idea of a haunted game.

tl;dr if you like atmospheric walking simulators, you might not want the horror story elements, but if you're patient it's still a fun experience.