Question: I've got a rough concept for a trading game in my head and I can't figure out what seems to be basic math.

My cities / space stations / trading posts shall have the following rules:

1. supply and demand are limited
2. prices adjust according to it
3. players as well as NPC traders drive the prices

So the idea is that if X produces less food than it consumes, then over time the price of food rises, and when it's almost empty, it skyrockets. While Y is a net producer, and the price falls over time. This creates a trade opportunity Y -> X whose profitability depends on how many people run the route - if many people trade Y -> X then the prices equal out.

To ensure that players don't simply collude on hoarding food just outside of X, waiting until prices rise and then selling, NPC traders would jump on the most profitable trade routes to keep price differences and demand within reasonable parameters.

I've thought about storage sizes and how prices can swing, but every formula I come up with fails some simple tests. For example, if the total storage of X is 1000 units when the player arrives, he can just buy 500, wait for the price to rise, then sell it again - profit. Obviously, that shouldn't work.

I tried several searches both on Google and here and on Gamasutra and while I found some ideas, I didn't find what seems to me should be a simple formula.

Answer: 
Don't rely too much on arrows.

Explosive and multiplicating arrows are fine, but the rest gives me a bad feeling in my guts you might end up with a too strong combination.

Imagine a FaZe / Hunting arrow. It would end your story in a single shot by simply killing the Commander of the Tech side.

Take only Explosive and multiplicating arrows and think of guerrilla tactics for the other occations where your primary weapons won't work.
Ewoks on Endor didn't rely on their primary weapon (infinite cuteness) but were also able to take down imperial walkers with real guerrilla tactics.

Your enemy is inside a house? Don't use FaZe to shoot them inside the building, but lure them outside and kill them in an ambush.

2 cents,

Alex
Personally I think that an explosive and cold combination would work as it would freeze and explode the target. Meaning no restriction of target meaning movement would be less restricted by barriers and the target could be both human and robot.