For the uninitiated among you, Modern Warfare 2 has a level-up system as part of it's online multiplayer. You level up by killing other players and performing objectives. Level ups unlock weapons, attachments, perks (very much like the Fallout perks but less imaginative) along with game types. The fact game types unlock means that most of the higher level players are actually out of your way to begin with (so the 'Gryphon' scenario rarely occurs) but of course the most popular game mode, Team Deathmatch, is unlocked at the start. So prepare to be mown down by missiles constantly.