A: It's easy to forget stuff! Searching for ';', which is a loose method but close enough, we're up to 711,000 lines, so it's just not possible to keep it all in my head now. I try to name my variables and objects consistently and memorably, and I leave enough comments around to remind myself of what's going on when I arrive at a spot of code. Sometimes it takes several searches to find the exact thread I'm trying to tug on when I go and revisit some piece of the game I haven't touched for a decade, which happens quite a bit. I'd say most changes are focused only on certain parts of the game, so there is kind of an active molten core that I have a much better working knowledge of. There are a few really crusty bits that I haven't looked at since before the first release in 2006.