I currently play three games, Eve Online, The Secret World and Guild Wars 2. Which of these games is not like the other? I would say Guild Wars 2.
Eve Online is the famously niche sandbox skill-based PvP sci-fi game that, inexplicably to those who don't play the game, not only refuses to die but is still growing almost 10 years later. The learning curve is considered extreme and in order to continue growth CCP is attempting to lessen the curve while keeping the complexity. The game that seemingly never ends, Eve Online's real-time skill system takes years and years to learn all the skills offered. As for content, the real content are the players themselves and the way they use the sandbox. The game only ends when a player becomes tired and moves on.
The Secret World is another niche game, but this time of the PvE variety. Set in a parallel modern world where all conspiracies are true, this horror-influenced MMORPG is also skill-based and while clearly a theme-park game I haven't figured out the order a player is supposed to go in once hitting a zone. Of course, after about 60 hours of play I'm still on Solomon Island so I'm getting the most out of my purchase price. Like Eve, once skill points are spent in The Secret World there are no resets. Also, the game is hard at times. Not Eve Online learning curve hard. Just hard getting through some of the obstacles. But getting through those obstacles gives a sense of accomplishment. For instance, figuring out the morse code mission the way I did made me feel really smart. And when I finally defeated The Boogy Man in the amusement park after the 15th attempt I cheered out loud. Sure, these events don't compare to the thrill and adrenaline rush of PvP combat in Eve, but I love them anyway.
That leaves Guild Wars 2, which I consider a guilty pleasure. Why? The game is pretty much a theme park that I really haven't found that challenging once I switched to playing a ranger. I die a lot sometimes but I pretty much brush it aside. And leveling is easy. While I was writing the series about the Eve News 24 botting expose I would go into Guild Wars 2 and just kill things as a break. I decided I needed cotton scraps to level my leatherworking so I decided to walk from Lion's Gate to Blazeridge Steppes because I heard of a good farming spot. I started out as a level 62 ranger and five hours and three game sessions later I was level 67 and I don't think I ever ran into a mob that was higher than level 50 along the way. While the game lowered my effective level while traveling through the lower zones, I received a lot of level 60+ drops along the way. These are really clever game mechanics designed to allow higher level players to play with their lower level friends. They also made the trip worthwhile.
So while I'm in low-sec in Eve Online probing down sites avoiding the faction warfare militias and facing complex puzzles in The Secret World, I can always go to Guild Wars 2 and relax by doing some farming. Farming I have to do by grinding mobs. But that kind of mindless game play does have a place as a change of pace.