Doom. You think of it sometimes when you're not doing anything. It just kind of pops in your head. And then you go find one of your copies or versions and play it. I also do this with Unreal. I don't know why. Am I alone in this?
This is the only time of the year that isn't hard to think of Doom. It's QuakeCon time, and in order to celebrate, Steam has a sale on all Doom titles. That's 66% off! The sale page lays out some pretty nice deals:
Or! Or you could own everything Doom in the Doom Pack Complete, which is only $13.59.