Adapting a game to Single player vs. Multiplayer

This point is something I have really struggled to get my head around. I would just love to know how in Left4Dead they account for four people being in a team, all with their own stress levels. I developed a single player game, a battle against an AI. This allowed me to adapt the AI itself, making it smarter or dumber, faster or slower, luckier or unluckier as required. It’s easy to see how and what can be adapted in a single player game, but in multiplayer the issues are vast: differing emotional states, differing play motivations, differing skill levels, and differing styles of play.  Player motivation determines whether a player wants to rush through a game to get to the boss fights, or the good loot, or whether they are more leisurely in their progress, values exploring the world, reading quest logs, studying loot etc. Skill levels obviously changes how quickly a player gets bored or stressed out of their mind, how do you deal with that in a multiplayer setting? Styles of play is something ahoodedfigure talked about at my GiantBomb blog, whereby players can be very destructive, and all they try to do is break the game, whereas others just play it within the frames of what’s intended. 

I truly don’t know how to account for all these things when attempting to adapt to the player’s emotions. Doing an average could nullify the emotional states altogether, keeping nobody happy. Giving one priority over another will make that player happy and the other frustrated with the game. It’s also important whether the game is coop or a pvp game. In a coop it’s easier as the players should (in theory) all have the same goal, to progress together. But then again, some people are all about the me, me, me, and others are quite the opposite. In a PvP situation you can’t adapt the fight one way or the other, as that would make the more skilled player feel hard done by, and the fight would not really be fair. 
 
Man, I find this bit tricky! Any ideas floating about out there? 

Should really ask Valve about this... :P
   

This point is something I have really struggled to get my head around. I would just love to know how in Left4Dead they account for four people being in a team, all with their own stress levels. I developed a single player game, a battle against an AI. This allowed me to adapt the AI itself, making it smarter or dumber, faster or slower, luckier or unluckier as required. It’s easy to see how and what can be adapted in a single player game, but in multiplayer the issues are vast: differing emotional states, differing play motivations, differing skill levels, and differing styles of play.  Player motivation determines whether a player wants to rush through a game to get to the boss fights, or the good loot, or whether they are more leisurely in their progress, values exploring the world, reading quest logs, studying loot etc. Skill levels obviously changes how quickly a player gets bored or stressed out of their mind, how do you deal with that in a multiplayer setting? Styles of play is something ahoodedfigure talked about at my GiantBomb blog, whereby players can be very destructive, and all they try to do is break the game, whereas others just play it within the frames of what’s intended. 

I truly don’t know how to account for all these things when attempting to adapt to the player’s emotions. Doing an average could nullify the emotional states altogether, keeping nobody happy. Giving one priority over another will make that player happy and the other frustrated with the game. It’s also important whether the game is coop or a pvp game. In a coop it’s easier as the players should (in theory) all have the same goal, to progress together. But then again, some people are all about the me, me, me, and others are quite the opposite. In a PvP situation you can’t adapt the fight one way or the other, as that would make the more skilled player feel hard done by, and the fight would not really be fair. 
 
Man, I find this bit tricky! Any ideas floating about out there? 

Should really ask Valve about this... :P
   

Valve spend a very large amount of time testing and re-testing their games, many features of the map design are there to help players, for example, the high wall around the starting area in No Mercy in l4d was put there after several playtests showed people would push teammates over the wall. If you keep getting large groups of players to play your game over and over you will notice things about how they play and you should be able to tweak level design or gameplay to slowly dial in on th eright balance for your game.
 
For more infomation on Valve's style of game development go here
http://www.valvesoftware.com/publications.html 

A few thoughts without necessarily tackling the meat of this issue:
 

• Games are wide in variety and different to each other (so far, so blindingly obvious).  Not every game will be able to suit a particular player however they are changed, by the very nature of what that type of game is and so maybe you don't need to accommodate for this.  Using the example of L4D, a skilled and headstrong player who just wants to charge through the game can't.  They'll be taken down if he doesn't have the help of his teammates no matter how good he is.  And similarly they need to defend the rest of their team and keep them alive because they won't survive long once one or two are dead.  This is the nature of the game and if someone can't hack it, then no amount of changing any aspect of the game will be able to accommodate them - certainly without being to the detriment of other players.
• Difficulty levels are there for a reason though not always well implemented.  Some games have adaptive ones that can be helpful by monitoring your performance in the game.  This of course can be done without monitoring the emotional state of the player though perhaps that extra information could allow the game to adapt more accurately.  In a co-op experience the difficulty level normally effects amounts of health and damage applied to each player and these can be mapped individually for each player in the same mission such as Gear of War 2 apparently does in its co-op mode.  This is a good way to go, though in GOW2 the difficulty level is picked upfront by the players - they might not be so keen on the difficulty to change differently for them on the fly if they have no control over it - it could feel unjust to them.  Also L4D changes difficulty by adding in more hordes of zombies or special infected or in L4D2 even changing the weather and layout of small sections of the map.  Changing the difficulty in terms of those factors couldn't really be done for each player individually since it will effect everyone at once (i.e. a good player is finding things too easy but if more zombies come then that penalises others on their team if they were already struggling).  In the case, again, it seems best solved by the player choosing an appropriate difficulty setting upfront so hopefully they're partnered by similarly-skilled players on their team.

The best option for a multi player is to make it completely different from the single player experiance. Call of Duty is a good example of this, in World at War and Modern Warfare 2 had their sp campaigns, but they were almost second thought and more like "how to use this weapon" tutorial instead of just drawing you in type like experiance. The MP section of those games is what draws you in and for the majority of the part you can carry a team death match game entirely on your own shoulders  unlike in left4dead where it forces you to cooperate with one another.I guess what I am trying to say that the COD MP experience is all about " me me me",but with that type of formula its alright. I love Left4dead, a friend of mine has convinced me to buy its sequel probably next weekend.