Psychonauts puts you in the body (and mind) of Raz, a telepath who dresses like a World War-era pilot and stumbles into a summer camp for kids with psychic abilities. Some fun (and occasionally deeply troubling) events unfold, with levels set inside the minds of some of the camp counsellors and other kids. We've written loads about it over the years, but instead of words here's a screenshot gallery John made.
The free offer is live now and runs for 48-hours, coming to an end this coming Saturday. Oh, and here's some words after all: John Walker once called this one Tim Schafer's last great game.
All of this comes without any update as to where exactly Psychonauts 2 is in development, of course, so we'll all just have to keep collectively crossing our fingers that it's going to be good. Please be good.