Guitar controller-compatible time-reversing rhythm shmup ... thingRetro/Grade may not be arriving on PSN until next year, but PAX attendees will be granted an early look at it during the convention this year. But what if you can't make it to Seattle? You'll have to settle for this new trailer, which highlights the game's rather unusual premise. Still don't get it? The final game promises a tutorial mode "to help people wrap their minds around our time bending concepts."