Aussie, I replied off the first page of the thread and missed your suggestion. Reading it over, I like some aspects of it -- like the fact that not all resource tiles are created equal. But when you start playing with percentages and fuzzy math, you start to get into unneeded complexity, IMO. (Especially in the case of a % chance of a resource disappearing, players absolutely HATE that kind of risk -- I know we can't stop people from reloading their game after every little thing, but if someone's oil spontaneously dried up you can damn well bet they'd reload until their luck turned around.)
I once read that the game of Civilization is a series of simple systems that interact to make a complex game. Food is simple:
tiles generate food, once you hit a threshold you grow. Research is simple:
trade is generated in cities, some of which is converted to beakers, and once you hit a threshold you discover a new tech. These are things you can sum up in one or two LINES, forget paragraphs. This makes them extremely easy to implement, and understand, and make game balance less cumbersome (which can take months for one small thing, trust me).
Chris Crawford on Game Design said:
There are few games that show any flair for simplification. 'Sid Meier’s Civilization' is one; Sid was so brutal in his simplification of history that I sometimes wince at the game's inaccuracies. Yet the result of Sid's design parsimony was one of the greatest computer games of all time. A lesser designer would have succumbed to the temptation to pile it on.
I think straight up hard limits would be better. You DO get this two line summary:
each resource tile increases the number of units and buildings you can maintain at that time.
E.G.: I have one tile of iron which increases my Iron Capacity to 20. A swordsman requires 1 iron, meaning that you can support 20 Swordsmen. I have an oil tile that increases my Oil Capacity to 25. Tankers require 1 oil. ... but there's no reason you couldn't extend this to factories (factories require oil), or even population in the modern era (2 cars for 4 people!). It all depends on the gameplay you want to create.
In that sense, it's like 'gold upkeep', except the 'per turn' is implicit. It's extremely easy to implement and understand, and way more balancable without too many complex hidden equations. It's pretty much one line of code! (One line per resource, I suppose...)
You can still have stuff like an open market for your surplus, and it would be much easier to implement too. If I'm running the free market civic, and I'm using only 20 out of 25 of my Oil Capacity, the last 5 would be available for purchase at a rate automatically determined by the total global surplus. (Definitely not under Mercantilism. State Property -- well, you would have manual control over who you sell to. And this could finally make for an interesting environmentalism civic -- "resources are twice as efficient" for example.)