Inspired by Delta’s post on “oil” as a weapon, found here. Long longago I read that and got to thinking, what if there were a fantasy campaign with some sort of weaponized flammable liquid (Greek fire, alchemist’s fire, wildfire, dragonfire, napalm, what-have-you)? But instead of merely limiting its use by making it dangerous to carry or expensive (options brought up in the comments of the linked post), you (also) limited its availability spatially? What if PCs had to go to a specific place on the map to get it? What if they had to use special measures to get their hands on it? The trope has plenty of precedent, and is easy to justify in-world.
Maybe the alchemist’s guild controls the production and sale of alchemist’s fire, and limits distribution to trusted customers. Maybe wildfire can only be bought from goblins at their seasonal Goblin Market in the depths of the woods. Maybe the only explosively flammable liquid around is dragon bile, which can only be procured from Mikel the Wyrm-Tamer. Maybe such a dangerous substance is controlled by the government, and you need a license or the right black-market connections to buy and use it. The point is that by going to the right place and doing the right things (making friends, performing favors, paying money, conducting a raid, etc.), the PCs can get their hands on a special resource and as a result, expand their options.
The campaign structure idea:
Then I got to thinking: You could probably build the backbone of a campaign from this conceit. One of the problems with “sandbox” or “crawl” campaigns is finding goals to motivate the players, especially at the beginning. But if the party knows that they can expand their list of available resources, and thus their range of options and efficacy, they have strong incentive to go off in any number of directions, and can happily spend time strategizing about which resources to pursue and what order to do it in.
So you make a list of resources that, by logic or fairness, would be available from the start: basic tools of the trade like some kind of weapon, some kind of armor, some source of light, rope, clothing, basic magical training, etc. Give this to the players so they know what they have – and next you’ll want to give them some clues about what they don’t have, and how they might get it.
Make a list of things that they’ll need to go through some effort to possess. Maybe standard arms and armor are available, but better versions (steel or other special material, high-quality products, magical items, etc.) are harder to get. Maybe a limited selection of spells is available, and the party needs to search for rarer magics for their magicians to learn. Maybe even mercenary hirelings, libraries of information, and other services need to be “unlocked.”
When you’ve got your list, you can start seeding your maps with not only the usual arbitrary caves, fortresses, tombs and dungeons, but also resource sites. That is, make sure the party will have the chance to expand their list of available equipment at some of the caves, fortresses, etc. Don’t fill the map with nothing but resource sites, of course, unless you want to eliminate the feel of adventure and discovery and make it into more of a puzzle, in which the players try to decide on the best order to tackle the available challenges.
Do make sure that the party starts out knowing about a few of the resources to be won and the sites to win them at. This information could be given in the form of entries in a rumor table, as explicit quests from NPCs, as common knowledge imparted as part of your opening exposition, or even as meta knowledge given directly to the players. There’s no need to show your whole hand, though. While high-level resources can be teased long before you believe the party is capable of getting them or using them effectively, knowledge of “hidden” resources can itself be a goal for the party to pursue or a form of treasure or reward for the characters to win.
As may have been obvious, part of the inspiration for this train of thought is computer games. It’s a time-honored tradition to have aspects of play “locked” until you pass the right hurdle, whether that be a boss fight, a puzzle, a skill challenge such as platform-jumping, or just some minimum of exploration or other proof of having played for a set amount of time. The question is how to fit these elements in a naturalistic and fun way into a RPG world instead of a video game one.