3. Gears of War - Seriously...
When the Xbox 360 was first released, it lacked a certain system seller by the name of Halo. Luckily, Epic Games had been working on this to really showcase the 360's online capabilities. Bringing the third person cover shooter to the masses, Gears of War quickly became Xbox Live's most popular game with sequels and spin-offs galore to follow. It also introduced the world to the first notoriously hard achievement. Seriously... requires you to get 10,000 kills in online ranked multiplayer. In a game like Call of Duty, 10,000 kills is nothing. Gears required a slower approach and so kills were harder to come by. It also didn't help that the game had major problems with bugs some people have had to almost double the 10k kill mark to unlock this achievement. Seriously... still holds major bragging rights though, especially thanks to the gamer picture you unlock along with the achievement.