I'm pleased to announce that the final bit of free DLC for Penny Arcade's On the Rain-Slick Precipice of Darkness 3 has just been released today on PC. The update for the XBLIG version of the game has passed peer review and should go live later today (probably this afternoon). The Mac & mobile versions are still being worked on and will receive the update at a later date. We'll keep you posted.
If Steam doesn't automatically download the update, try exiting and restarting Steam. That usually does the trick.
This update adds a new playable scenario to the game - The Beginning of the End. This scenario takes place before the main story of the game and features a new playable character, new abilities, new maps, new enemies, and even a couple new songs as well. To access the scenario, just select it from the main title menu. I do recommend waiting to play the new scenario until after you've beaten the main game since the plot will make more sense that way.