C-evo HOWTO: Technology

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This is the part of the C-evo HOWTO that describes technology.
==Introduction==
Civilization games cover the history of humanity from the end of the stone age up until the space age. To implement this, each nation makes discoveries ("advances") which improve their technology. 
This research is controlled by each player. After your first turn ends, a screen will ask, at the beginning of your second turn, what you wish to research. This window shows a handful of choices. It also has, in the upper left hand corner, a button that looks like a target or bull's eye. Pressing this button causes the number of technologies visible to greatly increase; you can now choose to "focus" your research towards a technology not immediately available.
Most technologies need other technologies developed first. The way technologies are dependent on each other is called a "tech tree" and is a very common feature of video games (not only do all of the Civilization games have tech trees, but also games like People's Tactics, Age of Empires, Imperialism, and Starcraft have tech trees).
For example, here is the tech tree to develop Monarchy:
* "Monarchy" needs "Polytheism"
** "Polytheism" needs "Ceremonial Burial" and "Horseback Riding"
*** "Ceremonial Burial" has no prerequisites — it can be developed at the beginning of the game
*** "Horseback Riding" also has no prerequisites
After clicking on the target/focus button, scroll down to see Monarchy, and select it. The list of advances will become much shorter and the box will ask what you wish to research, with the caption "Focus: Monarchy" and a list of all available advances that are prerequisites for Monarchy. You can either choose one of the technologies that brings you closer to having Monarchy, or click on the target-shaped button to change your research focus (or after researching Warrior Code or Map Making you can choose Military research).
To find out what a given technology advance offers, hold down the shift key on your keyboard and left-click on the name of the technology in question; the manual page describing the technology will appear. 
Some important early technologies to develop are:
* "The Wheel" (increases trade on many tiles that have roads)
* "Warrior Code (C-evo)" (lets you design better ground unit (C-evo)s)
* "Monarchy" (lowers corruption, increases research, though often with added costs for unit maintenance), and
* "Map Making" (particularly desirable on maps with a lot of ocean; allows longboats to explore the sea and carry ground units; but it adds trade to river tiles even where there is no sea).
==Tracking progress==
Use the function key F4 to see a list of what advances you have and what you are currently researching. If there are other nations, you will also see how your friends are doing and how any eliminated nations (or former friends) were doing at last knowledge. Similarly, F6 shows a series of charts; cycle through to see how your overall technology compares with others.
==Setting tax and research percentages==
At the beginning of the game, 30% of one's trade pays taxes (adds money to the nation's treasury that the nation needs to run and can be used to speed up unit or building production), and 70% of one's trade is devoted to researching new technologies. This percentage can be adjusted:
* Click on the image of a building in the lower right hand corner of the screen, just above the octagonal "end turn" button.
* Select "Economy and Tax". 
This window may also be popped up by hitting the "F10" key on your keyboard on some systems.
Unless you are at war with another nation and need to build military units or defenses fast (with rush-buying), adjust this number to have the lowest possible tax rate that doesn't result in the nation going into debt. At the top of the screen, you can see an icon of a treasure chest; next to this chest, the top line shows how much money your nation currently has and the line below it shows how much money the nation is getting or losing every turn. (In some situations you may lose less or gain more than what is shown there: The Oracle and overflow from completed buildings and units affect that.)
It is also possible, in this window, to give your society wealth. This, in addition to contributing money to your society's treasury (but not as much as taxes), decreases civil unrest and increases happiness in your cities. However, most of the time you will be better off leaving wealth at zero while adjusting only the cities that need it.
== Increasing technology research ==
Every time your nation discovers a new technology, the next technology needs more "bulbs" (research points) to discover. Getting more bulbs per turn is a matter of:
* Establishing a new city (but a new city does not contribute to trade (tax or research) at all until a Town Hall or courthouse is built in it)
* Upgrading a Town Hall to a courthouse ("Code of Laws" technology needed), which usually reduces corruption and therefore increases the amount of trade a town contributes to your nation.
* Putting roads on grassland, plains, prairie, and desert tiles your cities are using; this increases trade once your nation has “the wheel” technology.
* Other structures, such as the library, university, observatory, and research lab, which also increase research.
* Changing the type of government you have; this may increase research: switching from despotism to monarchy increases trade (by lowering corruption and producing more trade on some tiles); switching from one of them to a republic or democracy increases trade even more (but with different side effects).
== Changing government type ==
To change the government type you have to do the following:
* Research the technology advance that allows the government type in question. The advance needed for most government types has the same name as the type of government in question: Monarchy, Republic, Democracy, and Communism. The two government types where the advance has a different name are: Fundamentalism ("Theology" is needed for a fundamentalist government); and "Future Society", for which "The Internet" is needed.
* Start a revolution. This can be done by:
** clicking on "Yes" when you get the advance needed for a new government type and C-evo asks if you want a revolution
**going to the menu visible by clicking on the icon of a building in the lower right hand corner of the screen and selecting "START REVOLUTION".
For three turns, your government will be an anarchy; no money can be earned or spent and no management of your cities is possible, but harvesting and building continue. After three turns, C-evo will ask you what kind of new government you want.
Information about the various government types is available in the online manual; click on the C-evo logo in the upper left corner of your C-evo screen, select manual (or hit the "F1" key to get at the manual), scroll down the manual, and click on "government forms". The manual does not make the effects of each government type completely clear.
* Despotism. Generally an undesirable government type; you usually want to change to a monarchy as soon as possible.
* Monarchy. A good early government type; balances research with the nation's ability to wage war against other hostile nations. If you get the Newton's College Wonder you may be wise to remain a monarchy because it doubles research.
* Republic. A good government type during reasonable peaceful times; faster research but it's more difficult to go to war.
* Democracy. Even faster research, but not at all a good government to go to war with.
* Fundamentalism. A good government to have if at war with another nation and the war will be resolved before the nation you're fighting can develop new technologies. Slow research but no unit support and therefore popular with AI nations that want to win by force of numbers against more advanced, poorly-defended nations. 
* Communism is a good government for building units or building structures. It is not the best government for advancing technology. It may be just right when you are building spaceship parts because of the extra material harvested.
* Future society is good for the endgame when all of your cities do not need more population, and you need to either develop future technologies to defeat any enemy nations still around, or build the spaceship to win the game.
Tech