In 2008, Audiosurf came out on Steam, creating the psychedelic music game genre. If you haven't played it in the intervening three years, you're missing out on one of the coolest things in video games. The player selects any MP3 on their computer, then the game builds a unique level based on that song, which the player must then navigate whilst playing a block-matching, Tetris-like puzzle game. It's an incredibly compelling audiovisual experience, one with immense replay value and surprisingly lax system requirements.
For most of those three years, Audiosurf didn't have any real competition. No one was really sure whether psychedelic MP3 games were going to become a thriving genre or one-off curiosity. The Polynomial came out at the end of 2010 and indicated that the former may be the case.
Created by computer artist, programmer, and mathematician Dmytry Lavrov, the player begins a game similarly to how they would in AudioSurf, by choosing a song from their music library. Instead of creating a puzzle racetrack, The Polynomial generates a giant, fractal-filled polychrome galaxy based on your song or playlist. The player then flies through said galaxy from a first-person perspective, firing at baddies and collecting powerups. There's also a casual mode without enemies for just taking in the splendor. And oh, what splendor it is.
It's amazing how great programming and math can come together to make such a gorgeous game that will even run on a netbook. The galaxies are colorful, vast, and constantly shifting. Different types of music produce very different types of experiences (like AudioSurf), so fast dense songs will make more crowded galaxies than slow sparse ones. The speed, zoom, and shooting controls in the game give players a variety of fun and visually compelling interactions within the environment. A lot of the joy comes from trying to get the coolest possible view of the galaxy.
While they have very much in common, AudioSurf and The Polynomial have different feels to them. AudioSurf constantly forces the player to play its puzzle game, pumping up the visual stimulation with good performance. It's a more focused experience, but more limited because of it. The Polynomial can be an intense game if you choose a fast song and crank up the enemies in the options, but it can also be the opposite; With the enemies turned off, its barely even a game anymore, just amazing eye candy.
I've purchased both games and regret neither decision. They are different enough that all musical gamers will be satisfied. AudioSurf is a better game, and I would recommend it for hardcore gamers. For non-gamers, I would recommend The Polynomial because it's more visually stimulating and offers a wider variety of experiences, including ones that aren't strictly-speaking game experiences. Either way, you're in for a trip.