Last week, noisms of Yoon Suin fame wrote a blog post about a "single class paladin campaign" except he's not really talking about a single class paladin game, he's talking about how to operationalize honor for RPGs in a way that will facilitate and motivate a game built around honorable heroes doing honorable things. He admits that various character classes could be used in such a game, as long as the game revolves around matters of honor and correct, heroic behavior, rather than typical D&D "adventuring" or "murder-hoboing" or what have you. Instead of everyone being the Paladin class, they all are behaving by a code of conduct and in service to some greater power.
I was definitely interested in what he had to say, as it's something I've had to deal with with only limited success in Flying Swordsmen and Chanbara. Yes, FSRPG includes notes about the xia code, and what is expected of a wandering martial hero in Chinese stories/movies. But that's it. The XP system is still revolving around defeating enemies (of any type) to gain XP, and doesn't stipulate that the combats need to be won honorably. And granted, there are anti-heroes or those that skirt the line in wuxia fiction, and they don't necessarily need to be penalized.
I think I got a step closer with Chanbara. I re-conceptualized the carousing rules from Arneson's original campaign. But instead of saying you're spending your hard earned treasure on drunken debauchery and flashy displays of wealth until you're broke and need to go adventure again, it's explained as donating that hard earned treasure to your various lords, patrons, and clan to aid them in their endeavors. That's a step up from "hey, just role play it!" but I admit it still leaves something to be desired. Collecting the treasure is still a necessary step in play. If we're really wanting to make our campaign seem like the legends of King Arthur and Charlemagne, or of honorable samurai loyal to their lords and so on, "getting the treasure" seems out of place.
So, what sorts of rewards could we offer in a game that would encourage players to play Captain America instead of The Punisher? Galahad and Percival instead of Fafhrd and the Mouser? That's not an easy question to answer.
So what's been done before? Marvel Super Heroes, the old 4 color resolution chart game from TSR, had a huge list of dos-and-don'ts that could earn you Karma points, or take them away. The 1E OA book also had a big long list of "honorable and dishonorable" actions, which earned or reduced honor points.
I'm not a big fan of this method. For one, it's fiddly and arbitrary. It also requires everyone to be paying attention to a level of detail in the game that can hurt immersion. Finally, it polices play, rather than encourages it. XP for gold and fighting monsters encourages play. It tells players what the goal is, but not how to go about achieving the goal. Lists of "Thou shalt not..." doesn't give you a goal, it just mediates your choices in game. And giving a goal of "be honorable" doesn't spur action the way "get gold" does.
I don't have a lot of history with the Palladium or White Wolf systems, but from what I remember, Palladium has a lot of strictures for keeping your alignment a la the MSH Karma and OA Honor systems, but I don't remember if that had an effect on XP or not. It's been a while since I've done anything with that system.
For White Wolf, I haven't played Vampire, Werewolf, Mage, or Changeling. I've played Trinity and Street Fighter. In both of these games, at the end of a session (and the end of an adventure that takes place over multiple sessions), certain criteria are given or questions asked, and determine how much XP each character earns. This, I think, may be a better way to handle XP for the sort of "all paladin" game noisms wants to run.
For those that don't know, players get 1 xp just for taking part in the session, and then additional points if they can demonstrate that their character learned or matured in some way, a point for good role play, a point for sticking to the character concept well, a point for heroism (at least in Street Fighter, which I have). If I remember, for Trinity there was one criteria for using your powers to aid the mission.
This seems like the way to go to quantify honorable behavior to me. Make a list of criteria. The Chivalric Code. Bushido. The Way of the Jiang Hu. The Cowboy Code. Klingon Batlh. Probably best to keep it to under six tenets (the Cowboy Code as often shared on the internet these days has lots of pithy sayings that basically boil down to the same few concepts). At the end of a game session, go through each tenet and ask each player how they felt they upheld that tenet. Award chunks of XP for each tenet they upheld.
Of course, WW games use XP as a spendable currency to develop skills and abilities, rather than a measure of progress in class level, but that can be adjusted. If someone wants to keep the D&D class & level paradigm, either adjust XP values needed to level up down (divide by 100, maybe?) or tie the amount of XP awarded by the criteria to the level of the character.