Wow, I kinda can't believe this thread has taken off. John Hopson has worked with Bungie for years. [url=http://www.gamespot.com/articles/gdc-2009-quality-testing-halo-3/1100-6206812/]Here he talks about doing user research for Halo 3.[/url] While it's not the same guy, [url=http://archive.wired.com/gaming/virtualworlds/magazine/15-09/ff_halo?currentPage=all]here's another article about how user research influences game design.[/url] Human psychology is part of game theory. They're trying to understand "fun." I also maintain that using the changes to the Nightfall is an especially bad example, because the Nightfall rewards have always "sucked," and their primary motivation for changing the XP buff was to take away the incentive to doing the Nightfall first thing on reset instead of whenever you felt like it (unfortunately, "whenever you felt like it" became "never," but I still understand the decision on their part). Don't get me wrong. The infusion system is brutal. But, I see it as an idea that worked great on paper as a means of addressing player complaints about year one that ended up being a pain in reality. Flip side, the incremental gains or losses in light level also don't make nearly as much of a difference as 29 vs 30, 31 vs 32 or 33 vs 34, so at least there's [b]that.[/b]