|People throughout the land have to make money somehow.|
One of the things that I think about is what the player might want to do in the game, and how to accommodate those desires. Most games provide a system for fighting, so that's easily covered, but the reasons for fighting aren't usually discussed. Of course, the main reason is usually money, either directly or indirectly. However, the way that the character intends to make that money is highly variable. We can call these different ways of making a living "occupations", and there are only a finite number of them. They are also not the same thing as "character classes" or "archetypes" or other ways of designing a character's abilities. Anyone with any set of abilities can engage in any particular occupation, though perhaps some ability sets are more suited to particular occupations than others. Occupations, as I see them, are more like the basic assumptions of a game, and the more that are available in the game, the wider the opportunities the players will have. Here are the ones I can think of offhand that have adventuring possibilities, and what game systems need to be in place to make them viable.
Baron - this is a general term for those characters who are in charge of administrating a domain. However, see Homesteader. Needs a system of domain administration and probably a mass combat system.
Bounty Hunter - characters that take money to find and bring back other characters, whether dead or alive depends on the contract. Needs a system of investigation in order to find the target characters.
Cunning Person/Alchemist - characters that make magic items, such as potions or charms. Needs a system of magic item creation. See also Priest/Magician.
Explorer/Ruin Robber - the prototypical adventuring occupation. Needs a way to explore ruins or wildernesses. Traditionally, this is by hidden map.
Homesteader - characters who travel to uninhabited (or at least unclaimed by any civilized people) area and plant a homestead or colony. This usually leads to becoming a Baron. In addition to the requirements for a Baron, also needs a system of building up an area with buildings and other infrastructure and for discovering what forces might try to destroy, raid, or conquer the homestead. Those elements might also be useful for a Baron, but are not necessarily essential.
Mercenary/Guard - characters who go where they are told and perform violence when needed. Can't think of any special requirements.
Merchant/Pirate/Bandit - in this occupation, characters buy low and sell high. If they're lucky. Needs a system for generating and pricing trade goods. ACKS does this really well. Pirates and Bandits are just like Merchants, but they are willing to incorporate violence into their process of buying low (and sometimes of selling high).
Priest/Magician - providing spiritual or magical services to other characters. The exact nature of these services depends on the particular game system and setting. Frequently this includes varieties of healing or attending to matters of a character's spiritual state (aka "piety"), or otherwise assisting an individual or community. This occupation also includes character magicians who cast spells for money, as well as both mendicant and temple/professional priests.
Spy/Assassin/Thief/Ambassador - a variety of related occupations that involve deception and deceit in various ways. Requires a system to allow various types of deception, such as disguise, lying, stealthy movement, and so on. Oh, and poisons.
What other player occupations might there be?