Just Shapes & Beats
Just Shapes & Beats, the game about shapes, and beats. Once nominated for the most self-explanatory game title of all time, and didn't win.
It's a quirky 4 player coop musical bullet hell. The entire gameplay revolves around the music, as all the geometrical enemy patterns are orchestrated to it. It's what it says it is, just shapes, and beats.
Basically, it's a love letter to all the awesome chiptune musicians out there, an homage to their work in videogame form.