This is my second stab at writing about a multiplayer game, but I mostly played it safe while I experiment with new approaches to these games. The Halo 3 piece managed to capture what I think could be described as the 'Social Slayer' or casual side to the game. The competitive players felt left out and were quite vocal about this in the comments. This left me with a curious puzzle: either find a multiplayer game that never really developed a competitive culture on par with Halo 3's or find a game whose competitive culture is so different from casual play as to be a totally different game. The purpose being to draw out the core elements that generate these variations without rehashing a game I've already covered.
Plus I still think shotty/sniper is bulls***.
Left 4 Dead offers a remarkable example of the first type: a game that immersed itself heavily in what Richard Bartle would refer to as the prime era of a multiplayer game. It hasn't yet been taken over by Aggressive or dominating players. Once that happens you basically get stagnation and then a cut-off of new players to the game, you just have the pros refining styles or the occasional killer player type who breaks the design. Due to the enforced team-based play of L4D, dominating styles are difficult to develop because you never know if the person you're with is up to par. It's a really interesting design and one I thought worked very well, albeit the game lacked the variety needed to keep the procedural zombies engaging.
Games control this problem with a variety of interesting solutions. Halo 3 always matches you with someone at your skill level and divides everyone by letting you pick between "I don't really care" (Social Slayer) and "I am become Ur" (Ranked Matches). The point is to make sure you've got people who are in the same ballpark in terms of what they want from the multiplayer experience.
Left 4 Dead works for precisely the opposite reason. Zombies, 4 random strangers, and trying to find enough commonality to survive to the end.