2. World of Warcraft
Alright, I am breaking my own rule here a little bit. World of Warcraft came out in 2004. But I would argue that it didn't reach its behemothic status until well into this generation. So I am going to have it. (That and it didn't hit Europe, where I live, until 2005. So there!) I have a sneaking suspicion that in fifty years, when we look back to this era of gaming, World of Warcraft will be the most talked about game. I don't think we have seen one game dominate its genre so completely ever before. While there are other popular MMOs like Eve Online and Star Wars the Old Republic that have their following, they pale in comparison to WoW. 8 years after launch, the game still boasts around ten million subscribers, all paying monthly fees, for the privalige of playing in Azeroth. No one game has stayed that consistently massive through that long a period of time, but even on top of that, World of Warcraft is deserving of its place on the list for the abstract concepts it has brought into the medium. Showing the game world that subscription could work on a long term basis, WoW's influence is at the root of many of the pay structures that are being discussed now as we go into the new generation. Ideas of virtual ownership and currency in relation to the real world, microtransactions and free to play all owe a debt to WoW. Perhaps ironically, the latter being a tactic to even be able to compete with WoW in the MMO genre. So not only does WoW have a massive influence because of what it is but also because of what it inspired to oppose it.