This was suggested to me by Alistair Ramsden.
The basic mechanic: you have dice on the map that represent resources. As resources are used, the die value drops. Every so often, you roll the dice, refreshing the stockpile of resources.
The twist: on a refresh roll of 1, you remove the die.
So unless you have a mechanic allowing new resource dice to be placed on the map, the game will eventually exhaust all of the available resources.
Outlining how this might be used in Sun & Starship. First we identify how many resources we want to use this system. A practical limit, is that dice will actually cost money, and we will want to bulk purchase them in identifiable colours. So this does encourage us to build a system that requires less rather than more resource types. My first draft used Power, Capital, Yards, and Tech. My second draft refined this down to just Power, Capital, and Yards.
Power represents atomic power, and the associated trappings of a high-tech civilisation. Power can be used to make Capital, Yards, TECH for Fleet units and Credits (personal currency for players that does not have a role in the map game). Power can be damaged in combat.
Capital represents large quantities of finance that oil the wheels of commerce and government. Capital is the only resource that can be moved between sectors. Capital can be used to make Power, Yards, or Credits.
Yards are shipyards, and can be used to make SHIPs for Fleets or Credits for players. They could also have a role in a trading side-game, but I do not need to figure that out just yet.
Transitive costs occur when players have to make non-linear tradeoffs between different resources. I intend to make this happen by using triangular costs (another way of doing it would be with exponential costs). This is where the cost increases by one, for each additional unit you would like to purchase. So if the first unit costs one, then the second unit costs two, and the third unit costs three. So you have to expend six of resource type A to build three of resource type B. This means that even if a particular unit type (e.g. Knights) has a marked advantage over another unit type (e.g. Peasants), eventually the cost of the the better unit gets too high, and you want to start buying some of the cheaper units.
In a Grand Strategy game, where players/teams are alternating actions this system presents you with a few choices. The most efficient way to spend a resource to build other resources or boosting combat unit strength, is to just spend one resource at a time. If you need a significant number of resources quickly, then you can do an expensive build in one action. The presence of enemy forces nearby, might also encourage players to spend resources before they can be captured/destroyed.
One issue I am thinking about is whether or not players are free to spend the last point of resource on a resource die, effectively destroying the resource, or whether players are prohibited from voluntarily destroying resources this way.
From combat, I think 1-3 points of lost resources is reasonable. At least one pip off one die for a combat, two pips if a double is rolled, and three pips if a triple is rolled. Attacker chooses which resources are lost.
One thing that could be done in the interphase, is that all remaining resources are automatically used to improve Fleet values. So Power builds TECH, then Yards build SHIPs. Then the resource dice are rerolled. This should be fairly strightforward for the GMs to execute, and emans that in ‘quiet zones’ the Fleets will slowly build up even without active player attention.
How Many Dice?
Back of the envelope calculations, if we have three types of resource, and 100 map sectors, then we will need a minimum of 300 dice. Assuming we want some sectors to be more prosperous, then we may need 600-900 dice. That would get fairly expensive, although the dice could be reused in future games.