@stmartin
First congratulations on the new sub-forum HoTK really deserves a place of its own
Now about tech tree, let's state the exact problems we have here:
1 - A large empire is able to finish the tech tree around half the way through game time.
2 - A small empire has no chance of catching up in tech race and at some stage its troops are so ******** to constitute any real defense in face of the larger empires.
One more issue I see is that you can't really play according to your adopted belief unless you are a Unification leader. Division believers have limited options to win a victory condition that is compatible with their belief. Only cultural victory seems appropriate here.
For solutions:
AP has suggested some interesting solutions based on RFC.
- UHVs while can't be implemented in the same way as in RFC can be a base for adding more Victory conditions that allow smaller civs (especially Division believers) a chance for winning the game and gives larger civs a challenge. For instance if Nan Man has a UHV and they are about to obtain it Cao Cao can no longer ignore them and he has to divert his military effort to destroy them in time. Now some considerations for implementing UHVs is that they should be implemented in a way that doesn't depend on the map. Holding a specific territory for instance can't work. The reason is that we don't want to lose the variety of Random Maps and the different options for historical china map.
-If implementing a UHVs system is not a good idea for you then adding more general victory types would be nice. Some space race replacement can be nice. Religious (belief) victory can also be nice.
- Modifying research rate by empire size is another good idea. In RFC it is hard coded for each civ. This is ok there because Civs have a core empire territory and they lose stability when they extend beyond it. A more general approach can be utilized in HoTK. Let's say it is based on land area percentage so if you have 10% of land area you get -50% research modifier, i.e. you get -5X research modifier where X is your land area percentage.
- For smaller civs especially those who start already behind in tech race, tech diffusion can be a good boost. In Total Realism a civ that researches a tech known by all other civs gets 100% research modifier. This can be good in HoTK as civs have contact with all rivals quite early.
- I think belief system can be put into action to give civs some unique features as long as it is actually the main difference from a civ to another. Again Division civs don't really want to conquer all of China. They want to be left alone. They can then have unique (prerequired state religion=Division) more powerful units for defense. Their belief related buildings may give extra defense, etc.
- I know allowing settlers in the historical scenario is not a good idea but adding barbs or minor civs cities in empty areas can be a good idea. On one side they will allow smaller civs in remote corners of the map a chance to expand. On the other side it will make domination victory a possibility.