Guild Wars 2: warring with guilds. Actually, these days it's more about warring with other worlds rather than guilds, but that title was already taken back in 1939. Still, you can look forward to the next bout of competitive world-vs.-world action during the 2014 spring tourney, running from March 28th until May 30th.
The tournament will use a Swiss-style matching system rather than an elimination ladder; worlds are assigned points based on performance, then matched against other worlds based on their performance. The result should be that the best worlds are pitted against one another instead of being subjected to pre-arranged matchups. Players will be awarded tickets for participation after the dust clears, with more tickets going to players who are on higher-ranked worlds. For the details and more information about what you can spend tickets on, check out the official posting.