"Remember, for each project there's 3 Qa staff and millions of players" They have three options then: 1) Hire more QA people. 2) Let select players (say, moderators or maxed players) test updates on servers prior to them being released to the general public, with these servers being rolled back after. This is essentially 1) but much less expensive. 3) Continue with the current system and pretend it works fine. In their defense, we don't see huge bugs like with the update RoW very often, so they do presumably get most of them. The last huge bug I can remember was with monsters larger than one square becoming completely unagressive, even if under attack, which was last summer I think?