Awesome Games Done Quick is a speedrunning showcase that raises money for cancer prevention, and it's going on right now on Twitch. StepMania is an open source rhythm game which supports dance pads and keyboard input, and lots of customization. The two, together, today, were incredible.
All of the AGDQ speedruns are impressive—the skill in the Mirror's Edge run today was especially cool—but StepMania presents a clear, raw expression of speed and accuracy that makes it singularly mesmerizing. According to the commentators, the notes that receive a 'marvelous' rating (most of them) are being hit within a 45 ms window, and this is sometimes at BPMs over 250.
Notice how he has to avoid hitting mines. It gets better—here's where he hits 30 notes per second:
On Staiain's last song, the keyboard camera was shaking, adding to the impression that he'd entered the stratosphere:
And then Staiain introduced another high-level player, who took his seat, made the arrows spin around and go in two directions, and did this:
You can presumably learn more about StepMania on the official site, but it's currently down due to traffic sent its way by today's performances. Awesome Games Done Quick runs through Saturday, and is accepting donations for the Prevent Cancer Foundation. For more of Staiain's videos, check out his YouTube channel.