Before Brutal Legend, there was Psychonauts. Tim Schafer's exploration of the inner workings of the mind was highly regarded when it was released in 2005, but sadly wasn't quite the commercial success that many fans felt it should be. It has since been revived as part of the Xbox Originals program on Xbox Live, and now, as part of a deal between online service Good Old Games and Majesco, the (entirely DRM-free) PC version can be downloaded for $9.99.
The deal between GOG and Majesco also included Advent Rising, which can be downloaded for just $5.99.