Gary Gygax, creator of Dungeons and Dragons and the father of the thousands of role-playing games it spawned, has died. And while I think he made a bundle off of his ideas, he only got a small fraction of the value he created. After all, you can only copyright specific ideas, not an entire genre - even if without your work, the genre would not exist.
So this is a great time to let non-financial incentives compensate for positive externalities. Let's have a moment of gratitude for the great Gary Gygax. To the victorious dead!
HT: Eric Crampton, my former grad student whose enthusiasm sparked my last D&D campaign (using a house version of Gygax's 1st edition rules!).