Everyday Shooter is the ultimate genre orgy. We see a lot of stuff that subverts or explores the mechanical design space of a specific genre, particularly in the realm of shmups, but this here is the king crab of shoot-em-ups, the Kermit the Frog of shmuppery.
Gameplay is simple: arrows move, WASD directs your fire. You're a dot, and each level has its own musical arrangement, its own background composition, its own enemy movements, and its own score-combo mechanic. Mak calls it an album, and that's appropriate; it might be more appropriate to call it a gallery, since each level is really its own game, its own take on the genre. As Darius points out, each game is also an homage or composite of prior art, including one of Mak's own games.
The key differentiator from every other shmup yet made, or for that matter every other game, is the way the music and visuals correspond so keenly to the movements and timing of your bullet dance. Every enemy you hit and every point you pick up triggers a note. When they roll at pace it sounds like a smooth chord progression or rising arpeggio, which makes Guitar Hero look like total posing. Often they jumble and thrash in an explosive cacophony, which also sounds good, since we've been trained by two decades of metal and a decade of post-trance synth to hear beautiful patterns out in near-noise. If you could crank up the difficulty and swap out your own sets of .wav files, you could probably get it to sound like Nero's Day At Disney Land. Hey Jon, you gotta make customizable audio sets a feature at some point!
The macro-game is as simple as Sisyphus. As you earn points in gameplay, they store as currency that you can use to buy more starting lives, or unlock levels for single play, or neat features like paint-esque shaders, or the ability to adjust the contrast. You'll end up playing through the album dozens of times, moving further along as you get more skilled and more life-loaded. And as you finally roll that rock up the hill and complete the eight song, you will find yourself loaded with life. Abstract, expressionist in that each level is totally molded around a particular feeling, and yet, so concrete you could play with it like a kid plays with putty.
Update: speaking of Darius, he hacked up a Processing applet that let's you play with a tray of sound effects.