A few years ago, in 2006, Erin Catto created some code called Box 2D. It was a simple, free physics system the "math-obsessed PhD gamer" came up with in his spare time and gave away for free.
A year later, the iPhone was released. And suddenly his convenient, effective little code for implementing realistic physics in games was in big demand, and was being used by hit titles like Crayon Physics.
It was also used by Angry Birds. Now Rovio, the company behind Angry Birds, has sold so many copies of the game that it's worth over one billion dollars.
While Box 2D was released for free, and Rovio have no obligation to compensate Catto, you'd think that, as a gesture - especially considering Angry Birds' gameplay is built on physics - they would have properly thanked him. Maybe sent him a cheque or something.
But no. Catto says all he ever got was a hoodie.
"I have the sweatshirt but actually I have never worn it because it's red", he told NPR. "I generally don't wear red. That's a silly reason. If they would send me a blue one I would wear it!"
While you'd think all this would be grounds for him to be the world's grumpiest programmer, he's actually taken the whole thing rather well. Not only did Box 2D lead to jobs in the games industry (he now works at Blizzard, as a Principal Software Engineer!), but Catto takes pleasure just from other people's...pleasure.
"Almost everyone says ‘Jeez, Erin, you could have your own island now if you just charged for Box 2D!' The ironic thing about that is then I wonder what if Angry Birds used something else because I was gonna charge for it? Well, maybe if they used something else that wasn't as good, maybe Angry Birds wouldn't have succeeded. And I'm just happy that everyone is enjoying the games."