I will offer one disagreement: he's thinking about single-player games. There're also good jobs available on the server side for any online game (which is almost all of them these days). Server engineers don't need as much math as game programmers, and there are a lot of system and network administrators working in the game industry. Making games? Not exactly, but certainly working in gaming, with all the pros and cons that go with it.
In fact, you could argue we were solving the much harder problems in that game, since we had to deal with the massive scaling, while the game engine only had to deal with 10 people at a time.
Have you written anything on it?
I haven't written anything on it. I'm not convinced my piece of it was really interesting enough to warrant it. :) There were a lot of far smarter people than I on the team (it was one of the best software engineering teams I've ever worked on).
He's got about 3 million users. Not sure how many concurrent users he gets -- probably an order of magnitude or two less than LoL does.
Nevertheless, it all runs on I think one or two beefy servers. There's a very high fanout of game-available messages and they need to be addressed based on user-registered preferences as to the games they want to play.
From what he tells me, most of his secret sauce is network hackery. Batching up carefully-sized packets and so on. All that stuff I was basically awful at in uni.
Note also that all those careers are fungible insofar as you can take those skills outside the gaming industry relatively easily.