You seem like you'd be interested in a mod like Natural-Selection, which is my favorite for team-based playing. The clan-play in that game is absolutly top notch in terms of co-ordination and stratigy, but with enough skill and knowlage a good player can come out've nearly impossible situations.
ESF on the other hand, is more of a "fighting" genre of game. Fighting games let the individual's skill shine through more than any other type, as it's all based on knowage of the game and the ability to (pardon the term) "exploit" your charecter to the fullest of your own potential. You can take any charecter and with enough player ability you can make them killing machines, easily taking on a charecter with the same stats as the one you chose several hundred times in succession if there is a skill gap providing. True, skill gaps show through in any game as they should, but in the genre of a "fighting" game, it really shows the individual's playing ability.
In your example, killing 400 monsters with 3 friends is more enjoyable than killing 100 by yourself. This, is just an example based on beating up AI, however, and of course it's more enjoyable with human interaction. Many players, however, enjoy the challenge of fighting 400 monsters AND 3 other players who also have to be wary of the given monsters. Or, drop the AI altogheter, and pit them against what has the most potental to be more enjoyable than any amount of computer generated opponents, using various methods such as "free for all."
While I continue to further devulge into this rant, let me explain. AI cannot be played with in the same sense of a human player, as AI always follows a set of givens. They perform predetermined actions based on the actions of the player, whereas mind games come into play when one faces human opponents. It loses the "exploit the AI" feel and takes on more of a "Outsmart my opponent" feel.
I think the point that I may or may not have been trying to get accross is that some people enjoy the challenge provided from a constant threat and the thrill of knowing you're never really safe over teamwork/teamplay. You lose the feel of safety, sure, but you gain the knowlage that how well you do rests entirely upon your own shoulders without having to worry about taking care of others. Both styles of play are enjoyable, indeed, but to say one is better than the other would be rather judgemental. Each have their own perks.
but teamplay is good to couse you and your team can do "team work"by killing others thats fun...i
