Captain Anorak's Guide to Gaming
Character Purpose
It seems to me, one thing that often makes a crucial difference between good and bad roleplaying games is whether or not the characters have purpose. This applies particularly to player characters, but also in a somewhat different light to NPCs. (See also Purposeless Monsters).

Many games give player characters a purpose from the start. In Star Trek, PCs are normally Star Fleet officers who get sent on missions. In Judge Dredd they are law enforcers who patrol the streets. In Traveller, most parties of PCs will be the crew of a starship, who do whatever that starship is doing (be it military, commercial, whatever). In Vampire, PCs are vampires, facing all the daily challenges that are particular to the existence of a vampire (sunlight, vampire hunters, rival vampires, etc.). I haven't played Legend of the Five Rings, but as I understand it you play servants of the Emperor or of a Lord, who get sent off to go and do missions.

The genre that most commonly falls down on giving characters purpose is fantasy, by which I mean swords-and-sorcery (ie. pre-industrial level of technology, with magic). Original D&D never gave characters a purpose, but assumed that they would be a 'band of adventurers' who wandered around the world looking for adventures. This assumption has been carried on by most fantasy games since, like Dragon Warriors, Warhammer FRP, and Middle Earth RP.

I think the original idea of D&D was to recreate fantasy novels and mythic stories, with three particular forms in mind:
The wandering hero: Commonly in fantasy novels, a hero just wanders through a fantasy land for no stated reason, or for some conveniently introduced reason that means he has no place to go (eg. he was exiled). In his wanderings he has divers adventures, gets set upon by monsters, called upon to rescue princesses, etc. Moorcock heroes are sometimes wanderers of this kind.
Quests: The PCs either get sent or choose off their own backs to go and do some mission. For instance, they might hear of some monster that was terrorising people, and set out to end their suffering. Beowulf and Lord of the Rings are quest stories.
Treasure hunters: The PCs who would hear of some fabled treasure and go and try to get it to make themselves rich. Conan the Barbarian does this kind of thing.

The problem with quests is that they are single missions that someone gets sent on. They only last for one scenario. Once the quest is complete, there is no need for the game to continue. As for treasure-hunting, after a few scenarios the PCs will usually be pretty rich, so there is no reason for them to continue playing: their characters in this situation would by inclination probably retire and either get fat, or put the money into some venture which they deem worthwhile.

This only leaves wandering as a permanent basis for making a campaign. The PCs just drift about, and being jolly good sports they take up any challenge presented to them.

The conclusion I draw from all this is that cheap tacky fantasy novels such as those described above, like many things that work fine in fiction, cannot be converted into a roleplaying game that makes much sense, at least not regularly. If a group of players created a set of characters who had their own personal reasons for wandering about the world, that might make for one good campaign, but it's difficult to do that for every fantasy campaign. But most of the time players assume that their characters will be wandering adventurers without ever asking why, without ever even considering what reasons their characters have for doing this.

One particularly cringeworthy episode was when I joined an AD&D campaign. This was the first D&D or AD&D I'd ever played. I dropped out after two sessions because it was so bad. I had been offered to join an existing campaign, so I thought I'd give it a try. I wasn't really given any background to work with, just told, 'create a character,' so I did. I created a Thief. I was supposed to join this party of adventurers, so I told the GM that I needed a reason why my character would join them. At this point the character of another player turned to me and said, 'I'll give you 500GP if you join our party.' The GM and the other players then seemed satisfied that I had got my reason, so the game progressed without it ever being mentioned again. I soon discovered that these people were fucking awful roleplayers ('No!' I hear you cry, but I tell you it's true) so I left them, never to return.

I find all of this to be a terrible shame, because so much more can be done with a little thought. When I play any sort of RPG, I like to have my character do things because he has a reason for doing them. The idea of playing someone who just takes up whatever mission is offered by the scenario, for no good reason, fills me with dismay. I'm not saying that I want GMs to tailor their scenarios to fit my charcater motivations. Instead, I want to be able tailor my character motivations to the scenario. This requires that the GM decides why the PCs should want to do the mission, and then tells the players, and then the players create characters with those motives.

TYPES OF PLAYER CHARACTER MOTIVATION

Organisation - The PCs are members of an organisation, which tells them to do certain things. This can mean sending them on individual missions, or simply giving them a broad operational mandate which they then carry out on their own initiative. Individual missions means that at the start of each mission, the PCs are given their instructions for that particular mission by a superior. This could mean a single investigation in a police game, for instance. Then in the next scenario they get new orders for a completely different mision.

A broad operation means that the PCs are given an overall goal, and then get to plan all the individual missions themselves. For instance, in my game The King's Men, the PCs were agents of the King whose mission was to pacify an area with a population of about 3000 people. They reported the District Commissioner, who gave them information and advice (and on rare occasions, resources as well) to help them do their job, but really how they approached it was up to them. They planned their own missions and carried them out on their own authority.

An advantage of the organisation campaign is that it makes the PCs responsible to some authority: if they don't do their job properly, they're disciplined for it. A disadvantage is that it can allow the PCs too much access to backup from outside. If they can just call in airstrikes every time they need help, this can take a lot out of the game. The simple remedy to this is to make the backup unavailable (either the organisation doesn't have the reseources, or it's difficult to get the help to where it's needed within the time-frame of the scenario).

Organisation games could mean that the PCs work for the military, the police, a crime family, a shipping line, a church, etc.

Freelance - Freelances are people who do a certain type of job for private clients. The classic example is the private eye. This means that they're not responsible to an authority that gives them orders, but they are responsible to their own balance sheets. They have to complete missions to make a living. They don't have access to a lot of backup. They are also in a position to be leant on: in a private eye game, they may get themselves in serious trouble if they upset the police or any politicians or big crime syndiactes.

Settings for freelance games could include private eyes, smugglers, or investigative journalists.

Supreme authority - The PCs are the highest authority in the area where they live. For example, imagine a fantasy land which is divided into hundreds of little fiefdoms, many comprising only a few villages. They PCs are the lord of one such fiefdom and the nobelmen of his household, who are his companions-in-arms and the effectors of his will. Or they could form an equal council of oligarchs. They have to deal with any problem that threatens the fiefdom, be it rebellion, bandits, marauding dragons, or natural disaters.

The problem with such a game is the danger of the GM or players having to do accountancy, which would be very tedious. If the game took management of the fiefdom into account in any serious way, then it would have to have rules for things like agriculture (crops yields for a certain area of farmland worked by a certain number of men under different soil and climate conditions), population morale (what proportion of the population will want to rebel or emigrate under various conditions of food availability, taxation, conscription, etc.) and dozens of other factors.

It might be possible to leave all that out and just have 'mission' scenarios where some clear and present danger appears and has to be dealt with, but I think that in any such campaign, statecraft and land management would tend to come up naturally in the course of play. For instance, if the lord says 'I want to raise some more troops from my peasants,' or 'I want to repair my castle - I'll have to raise taxes to pay for it,' these factors become important.

Particularly, if the campaign involves rivalry with neighbouring fiefdoms, and there is some sort of long-term military conflict between them, then how those fiefdoms use their economic resources will be of major importance in determining the overall outcome. So to play this kind of game, you need a game system that covers managing lands, armies and societies. Without it you can't really play this type of campaign.

Personal reasons - The PCs have some reason of their own which drives them to want to do a mission. For instance, a friend of the PCs has gone missing and they want to find out what's happened to him, and save him if he's in trouble. This is fine for one scenario, but not for a campaign of unrelated scearios. In a campaign, this quest would have to be the underlying motivation that drives the whole campaign.

See also:
Yeah, But... My Character Doesn't Give A Shit! in Critical Miss Issue 6.