Flux takes inspiration from Pong, much like the first title in the series, Bit.Trip Beat. Players must reflect projectiles with a paddle, which fly from one side of the screen to the other in complex configurations. It's sort of like a reverse shoot-'em-up, where players are asked to defend the edge of the screen and hit all the bullets. How one succeeds or fails at this will drastically alter the audio and visual experiences.
Gaijin Games first released Flux via WiiWare in 2011, and has included it with physical collections of all six Bit.Trip games for both Wii and Nintendo 3DS. And now you can play it on your Windows PC or Mac in glorious HD.
On a personal note, Flux is far and away my favorite entry in a series I adore in its entirety. It's very much the culmination of an epic journey, and you can see the rest of the franchise etched into the framework of this stunning conclusion. If you haven't checked it out before, I implore you to do so. It's just that good. And if you have, well, why not take it for another spin?