In my experience, no, they don't write tests first, and in fact AAA game companies write almost no automated tests at all.<p>Instead, AAA teams have large staffs of cheap manual testers--high school and college kids who think they're getting paid to play video games. The managers in charge of these QA teams work their manual testers to the bone, encouraging them to work late and do unpaid overtime. These testers inevitably burn out, and but there's always a new batch of kids coming in to replace them.<p>When manual QA is that cheap, it turns the economics of automated testing on its head. Why maintain an automated regression suite when you have humans who will do the testing for you?<p>There's a similar effect on the dev side. A lot of inexperienced developers are willing to take a significant pay cut to work at a AAA game company, just for the dream of working on a AAA game. The devs, too, are notoriously managed as an expendable human resource. "You'd better keep working overtime, or I'll just replace you with another kid who'll work harder than you for less money."<p>As a result, AAA game developers burn out pretty quickly, too, leaving the game industry for other software companies that both pay better <i>and</i> offer a better work/life balance.<p>As a result, you'll find that a lot of AAA teams are relatively inexperienced. Sure, there's a core of long-time devs on every team, technical leads who can point the way, but it's not an environment where you can get solid mentoring on the best practices of software development.<p>Even if one team does pick up TDD, who knows if the same team will even be there in another year or two? Good software practices are regularly "rediscovered" on AAA dev teams, and then forgotten, as the team turns over and their tribal knowledge fades away.