It's a dual-stick shooter in the vein of Robotron 2084 or Geometry Wars. The gameplay is integrated with the music in a Rez-like fashion. Every "stage" of the game can be thought of as an individual track in the "album" that we call Everyday Shooter. Each stage comes complete with it's own unique music, visuals, and combo scheme which makes each one kind of a unique shooter in its own right. For me the kicker to this game is the synasthesia aspect of it. Basically every level is accompanied by a beautiful all-guitar soundtrack, and everything you do in the game triggers another riff or another chord, all of which harmonizes with the background music. In an abstract way, playing this game creates a kind of music that is totally unique everytime you play it.
Simply put, the combination and interplay of the game's visuals, the music, and the chain-reaction gameplay makes Everyday Shooter the perfect microcosm of everything that makes videogames unique as a medium.