There's a beauty to Flow that's unique, more than half a decade after it became popular with its release on the PlayStation 3. Its simple visuals and simple music combine with even simpler gameplay to make for an experience that's trancelike in nature, requiring little from you but offering a lot in return. Flow has since been eclipsed by the developer's more recent games--Flower and Journey--which fill a similar niche while improving on its core ideas. Yet Flow is as magical now as it was then, even if the magic doesn't last very long.
Flow might remind you of looking at bacteria under a microscope, though the visuals are more conventionally beautiful. Organisms swim around on a 2D plane you are looking down into, with larger creatures eating the smaller ones. These fishlike beings (similar to aquatic life such as eels and jellyfish) float against a simple watery background, providing a a beautiful combination of shapes both complex and simple, while floating particles add texture to the environment. A subtle blurring effect shows you what's below the layer of ocean you're on, giving you a good impression of depth even when you can swim in only two dimensions.
You control various creatures, one at a time, across various stages. Each stage plays out the same way: you begin small, you eat smaller creatures to grow bigger and evolve, and you attack bigger creatures until you can eat them, too. The world is divided into two-dimensional layers, with you swimming deeper and deeper down to progress. If you're like me, you will feel a natural desire to devour each and every living thing on your way down to the bottom, but nothing forces you to. There are no meters or time limits to worry about. Your pace is entirely your own.
You move almost entirely by tilting the controller in the direction you want to swim, occasionally hitting a button to perform a creature-specific action. The game's single-screen instructions (Flow's only instance of direction or assistance) say a button press gives you a boost, but this is not always the case. You might do something else, such as spin, and finding each creature's unique characteristic is part of what keeps you playing. Since each creature has the same goal (eat, evolve, and dive deeper) and each layer of water is visually similar to the last, the different abilities are your only real change of pace in the short amount of time it takes you to reach the credits.
The aesthetic walks an impressive line between simple and complex.
The only time Flow has anything remotely close to a challenge is when you go up against a creature of equal or greater size than yourself. The ensuing fight could have you tilting the controller more frantically in an effort to attack the enemy's weak points as it moves, but even this doesn't carry with it a threat of death or lost progress. There is no fear of losing; if you find yourself beaten by a creature bigger than yourself, you are merely sent up to a safer layer of water where you can recover.
While Flow does have an end, the journey is more important than the destination. The visuals and the music have a Zen-like quality to them, and the simplicity of tilting the controller makes for an almost meditative state throughout the game. While the actions you're performing could be seen as violent (considering everything boils down to one creature eating countless others), the experience feels more like a gentle float down a lazy river than a frantic swim through shark-infested waters, even during the most frantic fights. A friend or three can jump in at any time, but nothing is added to the experience, and, in fact, it's more placid alone. Flow is more of an art piece to be quietly admired than a challenge to be overcome with company.
Since there's nothing especially technical about how Flow looks or plays, it benefits little from the upgrade to PlayStation 4 hardware. It does run better, avoiding the occasional frame-rate hiccups seen on the PS3, and it's still beautiful and unique, though no more beautiful than before. If you bought the PS3 version, Flow is available to you free via Sony's cross-buy program and warrants a re-play, if only through the lend of the developer's later experiments in interactive tranquility.
Flow has adapted well to the PS4 ecosystem and holds up remarkably well, though it is neither as serene as Flower or as touching as Journey. Nevertheless, Flow is obviously the common DNA those beauties share. If you have somehow found yourself in a situation where you can try only one Thatgamecompany experience, this probably isn't it. But if you want a cool, oddly relaxing experience, Flow is still remarkably unique years after it first came out.