Cities XL introduces the concept of Resource chains - series of advanced buildings, related to each resource, which are unlocked only by achieving a certain level of its production in the city, not by population caps. Thus, similarly to Landmarks, these buildings will remain locked even in Expert mode, until your city fulfills the requirements for unlocking. There are two main types of resource chains:
This chain governs the basic production of the relevant resource, and is applicable to the four Utilities (with the exception of Electricity), and Agriculture.The system is as follows:
- You have 1 basic Tier 1 production building (for example Water tower, Fuel field or Farm). You need to build a certain number of these buildings in order to unlock one Tier 2 production building. For example, you need 3 Water towers to unlock 1 Water storage.
- You then need to build a certain number of Tier 2 production buildings to unlock one Tier 3 building. Again, in the above example, you need to build 2 Water storage buildings to unlock 1 Water treatment plant.
The production chain introduces an interesting twist into the production cycle, where you don't simply plop down buildings one after the other, but you actually need to consider their placement and use. It also ensures a realistic relation between 'basic' production structures (such as Landfill areas, or Farms), which are numerous, and 'advanced' structures (such as Incinerators, or Fertilizers), which are few, but strategically placed.
This type of chain is applicable to almost all resources and provides the option to specialize cities. Its buildings unlock after certain production level of the relevant resource is achieved in the city. You are able to build only one special bonus building per tier per resource, and also the total number of bonus buildings of each tier is limited (for balance purposes), so you'll need to choose carefully what you specialize in. Once you reach the limit of each tier bonus buildings, all others will lock, and they will only unlock if you destroy one of the existing buildings. We have three tiers:
- Tier 1 is a special office building. It costs 20000 c/mo to maintain and boosts production by 35%. Examples are the Fuel cartel, Electricity Inc., Merchant Guild, etc. This is the first tier to become available on relatively low production levels. Limit: 3 offices.
- Tier 2 is a special education institute. It costs 40000 c/mo to maintain, but the boost is 40%, and it provides additionally 5% Education satisfaction. Limit: 2 Institutes.
- Tier 3 is a special Research Lab. Costs 60000 c/mo, but boosts resource production with whooping 45%. This is the last bonus building to become available at very high levels of production. Limit: 2 Labs.
- Tier 0 - some resources have one more bonus building available. Industries, for example, have a special Storage facility. It generally boosts production by 20%, and is available before special Offices.
Thanks to the special boosts provided by the advanced buildings, the cities are able to produce almost double the output a non-specialized city achieves for the same number of normal production buildings. This is very important when it comes to Utilities, whose production buildings are all state-run, i.e. they cost the city money, instead of earning money from taxes. It is also worth noticing that this boosts come without any of the additional effects that increasing the number of production buildings has, for example more air pollution, or increased resource consumption. Of course, you also lose the potential job openings new buildings would provide (that's not an issue under normal circumstances, though).
You need to choose very carefully how you're gonna develop your city - building the right resource boosters might make the difference between the city being successful, and ending up in debt. You can try to specialize in many resources at the same time, by building bonus buildings for different resources, or concentrate on 1 - 2 resources and build all tiers of their respective boosters. In the first case you'll have a city producing a moderate amount of many resources, while in the second you'll be producing huge amounts of very few resources (I'm talking something like 200+ tokens).
And, of course, you have to keep in mind what resources your growing planetary empire needs most! The best results in Cities XL are achieved when many cities work together to ensure production of all resources.
For description of each resource's special buildings, refer to their relevant articles.