I am considering making a multiplayer sandbox game. I am currently thinking about an economy, which I would like to exist exclusively among players if possible and be actually active and realistic. I would also like to avoid side effects of the economy causing too much hoarding or concentration of power that can collapse the game/society.
The chief enemies to this plan are, as far as I can tell from experience:
1) Accumulation of junk in the world. Fancy terms for this are "inflation" and "deflation" but both are bad and both are because of different kinds of stuff accumulating, it is all the same problem.
2) Isolationism, I want people to actively trade, and have to trade, to get by. Minecraft is a good example of this utterly failing -- 99% of what you need makes no sense to trade for ever.
I'm wondering if I can run some ideas by people to see if you've heard of these being used before and if so, whether they worked or not, or if you think they will if they haven't been done.
ACCUMULATION OF JUNK
Unlike a typical RPG where stuff is generated (monster spawns) and destroyed (armor breaking and disappearing) all the time, I would plan to have my game would use a closed world -- no magical creation or destruction of matter at all. However, the resources begin locked away in the earth, so as people mine them, it still effectively leads to more and more accessible junk accumulating in the world. More building materials, metals, fuels, etc. The problem with this is that new players entering with nothing would be at an increasingly severe and de-motivating and stagnating disadvantage.
Some solutions I have considered to address this. Basically, all of them are aimed at not attempting to stop accumulating junk, but just making it less biased:
1) Fairly high taxes, property/income/sales. Then some central government (which doesn't do much else besides this) hands out fair shares of available tax dollars to new players and/or to dead respawning players + new players (you might also be able to will your next self some money, but there would be a death tax as well). Thus, as the game world progresses, newbies get dynamically more to begin with depending on how rich the world is, so they're never too far behind for when they started. Then just don't worry about accumulation too much.
2) Doing complicated things in game requires the help of other people, so people with ambitious projects pretty much have to hire employees and pay them to do gameplay stuff.
3) Have each new player have a special resource that you can't make more of, and that you need to do certain things. Similar to #2 but this is more like a passively applied resource. More advanced things require more of it than one person has, so they have to lease this resource from other players to do ambitious projects. Think of something like "psionic energy" for example (although that has nothing to do with my game as yet, this is an abstract idea) -- can't manufacture it no matter how rich you are, can only pay people for theirs. The richer the rich players are, the more they can competitively afford to offer for leasing, so newbie hel scales with wealth of the planet.
4) Crazier idea -- player avatars have limited lifespans, and also have children, and when you die (from accident or old age), you spawn into a randomly available (NPC at first) child via some set of rules, and get perhaps an allowance or something, then eventually inherit whatever the parents had when they die. This distributes wealth periodically among players, but not among families in the game world. This sort of interestingly gives players an incentive to make their COMMUNITY better off on average, to maximize their chances of spawning next time into a richer family. Need some way to avoid children murdering their parents all the time... also creates issues if too many people join too quickly. Also is bizarre.
ISOLATIONISM / FORCING TRADE
It's not an economy at all if you can get everything you need yourself. But this is rampant in all sorts of games. Minecraft as mentioned, but also RPGs like WoW, people trade a bit, but not at all routinely.
Solutions:
1) Clumpy resources - not every material and mineral is within 25 yards of you at any given point... Some things may be miles away from other things. In fact, routinely so. It may not take very long for you to personally travel such distances, but it still matters for trade because:
2) Bulk materials are difficult to move. No carrying of 40,000 metric tons of rock as in minecraft, for example, in your backpack. You want to move a traincar full of granite, you need an actual train car. So you as a person can run around and meet other people and do things without feeling like you are isolated, but your RESOURCES WILL feel like they are isolated... economically.
3) Moving a lot of bulk materials requires infrastructure that requires an upfront investment. This is important. #1-2 alone don't encourage trading. Sure, it might take a lot of effort to move materials, but if it takes just as much effort for some other guy to move rock to your home as it would you, there's still no reason not to do it yourself. But if infrastructure, like roads and railroads, is required and expensive, then that changes things. Me building a railroad form my house to every mine for everything I need is prohibitive. But me building one railroad to the nearest town with a market to move everything I need and everything I have for sale is affordable. I.e. a hub and spoke system costs much less in infrastructure than a cobweb of roads, and this forces trade.
4) Similarly, it should take a decent amount of capital to set up mining, so it's more feasible to have one guy with a mine for X who sells X to everyone than 15 redundant mines for X for each individual. You just can't afford to mine everything yourself (unlike 5 seconds in minecraft to make a pick to mine anything), but even a fairly new player can afford to mine SOMETHING fairly early on.
RUNNING OUT OF MATERIALS
A possible risk of doing things in the above ways is eventually just plain running out of stuff for people to mine. Solutions:
1) It costs more to move things further distances, to a significant degree, even after the infrastructure is in place (due to fuel, etc.). Early in the game world, you pretty much have to build an ironworks somewhere near a supply of charcoal, flux, AND iron ore if possible. But later on, you have more materials to fund further exploration and far flung industries, so you naturally expand out over time from the absolute best sites to the areas in between, in a sort of self-regulating way.
2) There are different grades of ores and things available, just like in real life. At first you have easy nuggets just lying around on the ground, but only in small quantities. Then people have to start digging a bit but not far. When they do, the seams will be more plentiful than the nuggest were, but require more processing (lower % per ton rock, even though total amount is higher). Later, you need to dig really deep, with expensive, collapse-prone mines and complicated machinery, and poisonous gases and heat and you have to process much larger volumes of ore for the same amount of stuff (or maybe veins are still rich, but harder to find them down there more wasted shafts).
3) #2 is discouraging to new players who may not have the know-how to design complex mining operations. This is a problem.
4) Recycling is fine too. Matter is not destroyed, although old machinery full of oil and unknown random crap and wiring and mud may not be as cheap to re-purify as the ore was.