Sharing the code just seems like The Right Thing to Do. It costs us rather little, but it benefits a lot of people in sometimes very significant ways. There are many university research projects, proof of concept publisher demos, and new platform test beds that have leveraged the code. Free software that people value adds wealth to the world.

The important point is that the cost of adding a feature isn't just the time it takes to code it. The cost also includes the addition of an obstacle to future expansion. Sure, any given feature list can be implemented, given enough coding time. But in addition to coming out late, you will usually wind up with a codebase that is so fragile that new ideas that should be dead-simple wind up taking longer and longer to work into the tangled existing web. The trick is to pick the features that don't fight each other.

The cost of adding a feature isn't just the time it takes to code it. The cost also includes the addition of an obstacle to future expansion. ... The trick is to pick the features that don't fight each other.

Programming is not a zero-sum game. Teaching something to a fellow programmer doesn't take it away from you. I'm happy to share what I can, because I'm in it for the love of programming.

Focus is a matter of deciding what things you're not going to do.

It is difficult to make good scalable use of a CPU like you can of a graphics card. You certainly don't want 'better or worse' physics or AI in your game

I really think, if anything, there is more evidence to show that the violent games reduce aggression and violence. There have actually been some studies about that, that it's cathartic. If you go to QuakeCon and you walk by and you see the people there [and compare that to] a random cross section of a college campus, you're probably going to find a more peaceful crowd of people at the gaming convention. I think it’s at worst neutral and potentially positive.