In KeeperRL the amount of resources you have is limited: trees don't grow back, all ores are shown once you have researched all geology technologies. There is a possibly a little exception with gold.
You get wood by chopping down trees or bushes.
The amount of wood planks per tile is:
- per Tree : 25-40
- per Bush : 5-10
Chopping down too many trees can summon a tree spirit.
You get iron by mining ore veins.
The amount of iron ore per tile is : 18 - 40
Iron is used to build rooms, usually with a military theme, such as the training room, the forge, ect. Iron is quite common, you can usually get it in large amounts from the very beginning of the game.
You get granite by mining granite veins.
The amount of granite per tile is : 18 - 40
You get gold by mining gold veins.
The amount of gold ore per tile is : 18 - 40
Gold is used to build statues and your throne once you can. It is the only way to seriously increase your population cap. Hoarding too much gold will attract bandits, and the throne itself makes your neighbors hate you more.
You need gold to pay your working creatures.
As of alpha15, no amount of gold seems to be decreasing over time, can anyone confirm this? It is possible that having treasure attracts more of them minions, though.
The alternative but surefire way of getting gold is by luring attackers into your keep and taking the ore from the bloody corpses, as they very often carry their purse with them. A defensive keep strategy will easily score a big gold count, while constantly rushing villages will leave you nothing if you don't go and fetch.
One interesting question: is gold dropped by invaders generated or is it part of your neighbor's stack? Can you get an infinite amount of gold and equipment from the incoming deceased?
You get mana by ordering creatures to study in the library.
Every creature studying gives you : 0.2 mana every 1.0 - 2.5 ticks depending on the creatures speed.
The alternative, as they say, is to kill or torture something innocent. While it is quite difficult to get prisoners as you tend to maim or get maimed (which you would have to send from prison to the torture task), the regular killing of cows, children or even incoming attackers will probably be a good source of hard-earned mana, while also making you very much hated by the population.