The five resources in the game are Food, Wood, Stone, Metals and Gold. These resources are neccasary to accomplish anything. Without a steady supply of each you will quickly find yourself unable to do anything. The buildings in the Field produce a continous supply of the first four of these at a base rate determined by the number and level of each type of building. These base rates can be magnified through research and wilderness conquest. Gold is produced by taxation of the population.
When something increases resource production by some percentage, N, that means N percent of the base rate. So a pair of 25% increases will give you a total rate of BaseRate x 1.5. (Not BaseRate x 1.25 x 1.25 like all you investment bankers out there might hope.) The base rate is determined solely by the buildings in the Field, each of which adds 50 x Level x (Level + 1) units of base production. (ie 100, 300, 600, 1000, 1500, 2100, 2800, 3600, 4500, 5500 for levels 1 through 10)
Food, used to feed Troops and Dragons, is the life-blood of the city. It is produced by farms, which are built in the Field. Food production can be amplified by researching Agriculture at the Science Center and by capturing Savanna or Lake wildernesses.
Early in the game, the equation is simple: more farms means a larger army. Later in the game, when huge armies might require millions of units of food, farm production will likely be insufficent. Instead, an aggressive strategy of stealing food from conquered Anthropus camps may be required. Attacking a high level camp can provide well over half a million units of Food.
If your troops are eating more food than you produce (ie, your hourly production rate is negative), you will not lose any troops from "starvation". Instead, your reserve will simply stay at zero, preventing you from performing any upgrades or training any new troops. This situation can be resolved by increasing production rates, losing troops in combat, or acquiring food through conquest and trade.
You get Lumber from building lumbermills in the field.
- Lumber is the resource you need the most for buildings and troop training. There is nothing you can build or train that doesn't require Lumber. It is your most used building resource untill you get to level 9 Fortress and level 7-8 Wall. It is also used to Research Woodcraft, Weapons Calibration, Metallurgy and Levitation.
You get Metal from building mines in the field.
- Metal is required for all but 3 types of research. With so many uses you may find yourself running low on Metals even though the individual upgrades, research, and troops you are working on don't seem to need much of it. So stay on top of Metal production if you don't want to be left behind.
If you keep an eye on your production and usage you shouldn't have much problem keeping up with demand for Metals. Building 4 or 5 Mines early will help boost your growth and still be able to keep up with research needs. Later on when you start to build a larger army with stronger units metal is used as much, if not more than wood, and is easily your most precious resource...
You get Stone from building quarries in the field.
- It is extremely valuable during the initial stages of building up your Fortress, Science Center and Garrisons.
- It used to be the case (and most older guides still state this) that stone lost its usefulness endgame and the number of quarries should be kept low. However the recently added endgame units (Fangtooths, Granite Ogres, Firemirrors etc.) all require a huge amount of stone (around 8k per unit), making it the most useful resource endgame.
Blue Energy is a new resource available with the release of the Spectral Ruins. This resource can be collected from the production in the Reaping Stones and purchased from the Shop.
A Soul is a new feature that has been introduced with the release of the Spectral Ruins.
If your troops die from battle when attacking or defending against another player, you have a chance to collect a fallen troop's Soul. A Soul can then be used to revive that troop.
Gold is earned from citizens of your city paying taxes. more Homes=more citizens=more Gold. Gold is used a lot for technology and you may be running low because a lot of your spaces are used to upgrade Garrisons and less for Homes. You can also get Gold by selling resources in Trade.
Gold can also be looted from Anthropus Camps. The higher the level of these camps, the more gold can be looted. Be sure to add Armoured Transport or something like that to the attacking army, to be sure you can carry enough resources back to your city.
Rubies are the special in game currency that is used to purchase different things to further enhance the game in the favor of the player. Rubies may be purchased or earned by completing a variety of your "free offers"(even the free ones would require personal information and some money).