To me games with co-op driven into their mechanics tend to succeed in places where confrontational games fail. Theirs still the focus of overcoming some obstacle, but in this case it isn't the other player. Players either work together against an AI deck or against the games rules itself in order to win. They either win or lose together as a team, to me that makes for a more fun experience. When your game is fun to play it's more likely to be played over and over again, right? Take games like Left4Dead, or better yet, Sentinels of the Multiverse. In either case it's extremely difficult if not impossible to beat the game by yourself, the support of your friends is absolutely essential.
With L4D there are too many zomb--infected roaming around that can easily overwhelm you and your measly pistol and painkillers. You have to rely on your partners to pick you up when you're downed, heal you when you're running low on health kits, save you from falling off a ledge, save you from a swarm of zomb--infected (assuming you're blessed with competent partners of course) if you plan on seeing your name during the end credits after all the remaining survivors have escaped. I've never had the chance to sit down and play SotMV myself, but from what I've seen and read of it the game runs a similar set up. However, instead of a zombie horde to face there is a central villain, giving players a tangible goal to pursue in lieu of their defeat. Other than that the only major difference I see in the games is that you can still ''die'' for good in L4D, as there are no rescue closets during the final act. Does this hurt the game compared to SotMV, where ''death'' only means that you're downed but not out?
Long story short, what do you guys think makes a good cooperative game, really really good? What mechanics in any cooperative game you've played do you favor the most?
