Gears of War 1, 2, and 3 on the xbox 360, its a shooter. I competed mainly in a thing called Major League Gaming, or MLG. They dropped the game in 2010 because it wasn't nearly as popular as other games that attract more viewers, advertisers, etc. I was considered a professional in it from 2008-2009, which isn't really saying much in the grand scheme of things. There were four players per team in a double elimination format, and the events usually held up to 128 or 256 teams and the top 8 teams (32 players) were considered professionals. You did get some cool stuff like access to an exclusive lounge area, some jerseys, and a $200 stipend per player that could go towards airfare, hotel, etc.
Probably just explained that a lot more than anyone cares to know, and that barely scratches the surface.