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Supply and Demand Mechanic?

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dnddmdb's picture
Joined: 01/06/2009

Man, it's been a while...

Recently, I've been working on a game in which the Players are rival mining corporations on an alien planet called Prox, searching for a rare material simply called "Ore". In it, Players play using a Rover to prospect certain territories (Hexes) for mining, with some territories more favorable than others (When you Prospect, you roll a certain number of dice depending on the area, and then that territory is given that many Ore counters (you can only do this once)).

Then, you build Mines and Defense Towers to Mine you expand your "empire" or attack others. As you collect Ore, you sell it for Money, which is needed to win the game, as well as build Mines and Defense Towers. There are 12 Rounds, each Player getting 1 turn per round. At the end of the 12th Round, the Player with the most money wins.

I have it made currently that the sale of Ore is completely optional as to when to sell and quantity sold, and I want to make a good system to allow this to be a strategic and important choice. Currently, I have a mediocre system of simplified Supply and Demand, where:
1. The Going Rate for Ore constantly increases by a set amount (Number of Players). This represents Demand.
2. Depending on the amount of Ore sold that Round, the Going Rate decreases by half the amount of Ore sold in all.

This system, to me, doesn't seem adequate enough to make the decision very strategic. I was just wondering whether or not anyone had any ideas for improvement or had seen better systems from other games. I would like to avoid luck, if possible.


Joined: 07/08/2009
Luck/ Strategy.

What about a system where at the beginning of the turn-- round,sale phase . . . not sure how your game is set up-- each player contributes something to the price: Maybe they have a set number of numbers. Maybe they have different sized dice. Maybe you have a card system in the game, and you could add numbers to those. Maybe they just have 0-3 rocks hidden in their hands. And the extent to which this effects the price could vary, but let's look at a simple case where it's just the sum of everyone's attempt to influence.

Each player would secretly add a certain number to the ore price, then the price for that turn (could be next turn?) becomes the sum of those numbers. That might let players who aren't selling that turn contribute not much, or if a player wants to force others to sell for some reason, they could drive it higher. . . I'm sleepy, but something like this might be interesting.

Or, what if at the beginning of every . . however many players are playing . . . turns, the players place numbers on a track, which will be the price. So, maybe I think I will take a while to mine, but will get a lot when I'm done, so I put the "4" on the end of the track. Maybe someone else has a huge stockpile from last round, so they put the "3" right away.

With that, there might have to be some inhibitions to when or when not to sell . . . though needing to buy new stuff might be enough.

I'm tired, but I hope this was coherent enough, as a musing!


ilta's picture
Joined: 12/05/2008
I'd check out "Buy Low, Sell

I'd check out "Buy Low, Sell High" which is a reworking of the Knizia game "Palmyra." The game is entirely about the supply/demand mechanic inherent in the stock market (originally, in antiques), but you might be inspired by -- or even be able to cherry pick -- either of the game's basic mechanisms:

1) A "chain" of values on which a few little markers are placed. When you want to buy, you take the highest-priced marker and pay that value, when you sell, you add to the bottom of the chain, collecting that value. It's a bit fiddly in a physical sense (lots of markers to knock over) but very elegant in a rules sense. The chain moves as players buy or sell with varying rates of interest; it can max out or bottom out, resulting in lots of buys at the top price, or lots of sales at the bottom.

2) Cards that artificially move the entire chain up or down.

It's a great little game that would make a good subgame in something more complicated, like the one you're designing.

dnddmdb's picture
Joined: 01/06/2009
Hmm... Something I Could Work With

Thanks to both of you!
To Scifiantihero:
I am definitely thinking something along the lines of Players adding to the cost, but I want to make a way that one person wont leave the others in the dust. I think I will make a sort of VP system, where depending on what you do in one turn, you can influence the price, but I'm not too sure.

To ilta:
I checked out "Buy Low, Sell High" and it seems pretty cool. The only thing is, my game doesn't involve buying Ore, as you mainly want to make money by selling.

I am currently thinking of a system like Power Grid, but in reverse, where whenever someone sells, the going rate for Ore decreases, so people will sell less. The only problem would be that once the market gets low, it would stay fairly low.

Thanks for the info, though!

ilta's picture
Joined: 12/05/2008
Yeah, that makes sense.

Yeah, that makes sense. If players are only selling, you would need a "reset event" to move the price back up.

Some ideas:
- a partial recovery at the end of each round
- a partial recovery at the end of each player's turn
- whenever a card of a certain type is played, the price moves up [x]
- "influence the markets" as a choosable action rather than mining or upgrading or whatever else you can do in the game

Most nterestingly, I think, is the choice that the going price of ore moves up after any round (or turn) in which NO player sells (or in which the active player doesn't sell). This creates a really cool "chicken" dynamic - you can wait and hope nobody else sells, and the price goes up, but it's a risk that by the time it's your turn again the price will have plummeted because everyone's flooded the market.

Keeping people from being left in the dust can be accomplished, in part, by giving the last-place player first choice as to whether to buy or sell. Smaller, more nimble companies and all that.

domd's picture
Joined: 12/15/2008
Ore maybe...

dnddmdb wrote:

I am currently thinking of a system like Power Grid, but in reverse, where whenever someone sells, the going rate for Ore decreases, so people will sell less. The only problem would be that once the market gets low, it would stay fairly low.

I had considered responding with a Power Grid reference, but figured it was too obvious. Now that you've brought it up though, it is a great mechanic to work from when modeling a market condition. To your point about a low market price, however, you might consider a mechanic that influences market demand beyond the scope of the players in the game. In other words, if the game does not necessarily define the universe in which it is occurring, then it would be okay to assume that there is demand for Ore beyond the scope of the players in it. Could be that each turn adds demand based on a schedule, or a die roll, to represent population increases or currency fluctuations that occur in real life all the time. Or, there could be a "scrap recycling" mechanic whereby the more scrap that is recycled the less ore is needed to fill out existing demand, but if scrap supply is low then demand for ore goes up.

I used to work in a ore-handling operation that fed a number of blast furnaces in an ironmaking facility, so on some level I have a rare appreciation for your game. Keep up the good work.

sedjtroll's picture
Joined: 07/21/2008
Supply and Demand

I struggled with Supply and Demand in Terra Prime as well - I had a really neat mechanism sort of like Power Grid's resource market which I really liked, but simply didn't work. I ended up replacing it with a simpler "demand tile" system which ended up working great for me. I have demand tiles which indicate what is in demand, and when those slots are filled, you can no longer sell that resource.But that may not work as well for you, as you only have 1 type of resource (as opposed to 3 or 4).

Power grid was already mentioned, that would be a system where as players sell Ore they place it on a Demand track and collect the indicated price. As more and more Ore is sold, the price goes down and down, then at the end of each round (like in power grid) the market would be adjusted. In PG items are added while for you Ore would be removed from the track, bringing the price back up a bit. In Power Grid the rate at which the market changes depends on the phase of the game, you may consider something like that, thematically whoever is buying all this Ore is using it up, and as time goes on they need more and more of it. That would clear up the Demand track more in the later game when, presumably, players would be producing more Ore than they were in the early game.

I just read about the new online Planet M.U.L.E. site where you can play the old computer game M.U.L.E. online. It describes the supply and demand system there, which is surprisingly similar to yours! Players mine and then sell off Smithore, which the game uses to make M.U.L.E.s - which players in turn buy in order to build factories (to mine Smithore, Crystite, Food, or Energy). There's a Demand for M.U.L.E.s based on number of players and how many un-exploited plots of land they have (including what they're likely to get next turn), and that demand less the number of M.U.L.E.s already available affects the demand for Smithore.

I think the key here is that SOMEONE needs to be eating up the Ore that's being produced in order to maintain demand. If players aren't doing it, then the game has to. It's up to you whether that should occur on a regular schedule (like POwer Grid), or semi-randomly. For example you could have a  deck of Demand cards, and after Ore is sold you flip one up to indicate how much Ore is consumed. then you can control how much demand "comes back" on the average, and round by round it will fluctuate a bit.

I will caution you about 1 thing though - if each player gets less money than the last, then be sure to allow players to sell things 1 at a time rather than all of their stock at once or the first player to go will make MUCH more money than the last player!

dnddmdb's picture
Joined: 01/06/2009
Good Ideas

Awesome! I am loving this input.

To ilta (again)
I like your "influence the markets" idea. It would be a good option because the only other Actions I have so far are move your Rover (which Builds Mines and Defense Towers), Build Buildings, Attack Buildings, and Prospect (determining the amount of Ore in a territory). If you can't do any of those, this would be a good option if you had a lot to sell.
Also, as far as leaving a player "in the dust" is concerned, I think I will change the rules so that the person who sells the least goes first next round, and the one who sells the most goes last next round (likewise with the other players).

To domd
I think I will also increase the going rate every round by the number of players, plus the round number. This will allow a steady increase of demand as the game progresses (as more Ore will be sold each round, most likely).
BTW, I am glad you feel that way about my game. Thank you.

To sedjtroll
I think that my response to domd and ilta sums up what I should say to you.
About your last paragraph though, my one-who-sells-less-goes-first idea keeps the game in a sort of bluff, where it would be unfavorable to sell most of your Ore until very late in the game.

Thanks to everyone for the responses!

sedjtroll's picture
Joined: 07/21/2008
dnddmdb wrote:my

dnddmdb wrote:
my one-who-sells-less-goes-first idea keeps the game in a sort of bluff, where it would be unfavorable to sell most of your Ore until very late in the game.

This assumes there's a significant advantage of some kind to going first. If that's the case, then I think it could be very interesting to decide to sell only just what you need in order to maintain a favorable turn order, keeping some Ore to sell later. In one respect, this would make you very illiquid (all your assets are tied up in Ore that hasn't been sold yet) and therefore less flexible in your plans. Also, depending on market dynamics you could be waiting for a better deal - if demand will increase later in the game, you may profit more by warehousing your Ore until later. Ideally, if everyone does that then when everyone tries to dump their Ore, demand will fall and some players will NOT do as well. So you can probably make out better at least some of the time by selling early - and it probably depends on turn order, how much Demand will change, and how much Ore everyone has.

That sounds like it could be VERY interesting!

dnddmdb's picture
Joined: 01/06/2009

Thank you! There will be advantages to going first, such as being able to have your pick of territories (some territories are more favorable than others).

I'm glad that this is shaping to be a bit better than I had first anticipated! :)

Joined: 12/10/2009
A different way to drive the market

The market starts at say 30 monetary units per ore sold, for every so many ore sold into the market, the price goes down. But here's the hitch. The ore is also used as a resource to improve things about your defense towers, or mining machine.

So as the price of Ore is driven down, suddenly someone with a dearth of funds can make a calculated decision to buy a bunch of ore and improve his machinery etc. The ore price would rise at the same rate that it declines.

dnddmdb's picture
Joined: 01/06/2009
Definitely Different

That is a very different take on the game, and it would most definitely work (rather well, if I do say so myself) but the way I have the game set up currently is that no Defense Stations or Mines are upgradable.

I will, however, consider your approach. Thanks for the idea!

Joined: 12/23/2009
I'm sorry if it's already

I'm sorry if it's already stated, I only roughly scanned trough this thread, but like stated I think the Power Grid mechanic is very neat and elegant, however my idea;

The higher the ore supply the lower the price and visa versa, this is how, I assume, you want the market to work?

To spice it up with out randomness I would advise the following features;

1. First of all make Ore a requerement for building towers and mines etc. (Dunno if you already had that?)

Then the questions moves from selling as much Ore as possible to getting Ore at the right time, i.e. you all need ore and you can use your own ore to built defense towers or whatever but it might be more profitable to waite and sell ore first. Wich should be intresting.

Now ore is something you wanna produce as much as you can and sell as much as you can, but you also need it.
Without extra game elements it would be like this.
Get ore (early stage)>reinvest ore (early mid-game)>get more ore (mid-game)>sell ore (late game).
Pretty lame.

So to change the flow of this principle the market has to fluctuate so that it can be more profitable to sell your ore first and then later buy more for a lower price.
You can naturally do this by making ore scarce in early mid-game so that demands go up and prices or benefits go up, now playes will be tempted to sell there ore and rebuy and reinvest later (meaning they can reinvest more, cause the investments will be cheaper and/or they got more money), while other players are willing to buy ore at a higher price but in return get a longer time of benefiting from there upgrades.\

So far the Ore market is just player generated if you use the Power Grid system like this.
Fields where ore can be placed with the amount of gold you get if you sell it to that field. It will fill up as follow:

2 ore:2 gold ; 2 ore:4 gold ; 2 ore 8 gold ; 1 ore:5 gold ; etc..

People buy the cheapest ore first and free spaces can be filled up by selling players wich get more money the less ore there is and the higher the free spaces go.

But to further fluctuate the players market (except from the game choice early investments or late investments) I would advice to allow for the creation of treaths.
For example player 1 treathens to attack player 2, player 2 has no choice except to defend himself by buiding a defence tower, wich will cost him ore.
Gameplay wise this could turn out like this;
Player 2 sells his ore in early game when there is a higher demand, player 1 buys this ore, but instead of reinvesting it (wich would be for example the most profitable choice) he builts an army and treathens to attack player 2. Player 2 now has to buy ore again at a higher price (because player 1 buyed all the ore player 2 sold) and has to built a defence tower. This way player 1 cancels out his disadvantages to player 2 buy not reinvesting his early bought ore.
Ofcourse if you want a game with more player you need to make sure that the third dog doesn't run off with the bone.

More variables to the market workings could be some lesser elegant solutions like a giantic space craft that enters this mining planet and buys up all ore there is.
Player could somewhat manipulate the coming of this spacecraft and might also be able to manipulate in wich order they may sell the ore to renewed emptied ore for gold spaces on the board.

In short, let players control the market for ore and create variables into the gameplay that have an influence on this market as to create variety in the Ore market.

I hope this long text was any help to you and good luck.

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