I'll keep that in mind, thanks.
EDIT: I have been notified that Venice's new Palace grants 3 Food instead of 3 Science. I will fix this soon.
EDIT: Uploaded version 4 of the 4UC. This issue is fixed.
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Jan 16 Edit: I have updated both mods to "Version 5". Here are the changes:
Now compatible with Single Unit Graphics mod.
Mongolian Yam now replaces Stable instead of Caravansary (this makes it compatible with Improved Caravansaries mod). Yields altered to balance.
Byzantine Hippdrome no longer uses up a Horse resource (it was competing for resources with the Cataphract UU). Now requires a source of Horses or Ivory like a typical Circus. Removed +1 Gold yield.
Spanish Mission no longer gives Missionaries +1 usage of Spread Faith. The 25% passive spread bonus is strong enough.
French Salon now replaces Zoo instead of Windmill. Yields +2 science instead of 10%. This is to encourage building a wide empire.
Shoshone Tipi yields +1 Culture and +1 Production by default (+1 Culture bumped earlier for simplicity's sake). Construction time increased.
Ottoman Siege Foundry removed.
Ottoman Great Bombard UU (Cannon) added. It has a 300% combat bonus against cities (instead of 200%).
Improved artwork.
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January 21 update: I have noticed that the new Ottoman UU is missing a line of code, which allows other siege units to obtain its promotion. I will fix this in the next update.
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January 24 Update: The 4UC has been updated to version 6. This update fixes a few lines of code.
I'm quite happy with the two mods at this point. The 3UC and 4UC feel nicely balanced, fairly interesting, and historically representative. I don't plan on making any major changes to the mod after today, although I will stick around to patch any errors that might show up, tweak balance issues, or to increases compatibility with other mods.
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January 28 Update: I recently received some informative feedback on these mods and have decided to make one more update. Both mods are now on Version *7*. There is one major change and many underpowered components have been buffed. Here are the following changes:
Mayan Obsidian Warrior overhauled. The Spearman-to-Longswordsman upgrade path caused the Mayans to become needlessly dependent on Iron. It is now a Swordsman that has a 50% anti-mounted promotion. This allows the Mayans to retain their basic defensive units, while providing them with a stronger alternative if they have access to Iron.
Aztec Sacrificial Altar now yields 2 happiness instead of 1.
Viking Longhouse now gives all melee units a 15% combat bonus when attacking, supporting a Domination Victory. (+2 Culture wasn't enough).
Iroquois Rusher now ignores movement costs instead of having 3 movement. (This means that they can't sprint over flat terrain anymore, but instead aren't slowed by rivers).
English Playhouse now has free maintenance instead of +2 culture.
Mongolian Ger now gives land units 15 xp instead of 10 xp.
Portuguese Casa da India now yields 8 gold instead of 4 (since it can only be built once).
Ottoman Hamam now yields 3 Happiness instead of 2 (since it can only be built in some cities).
Oromo Warrior no longer gets extra XP from combat (the two free promotions were enough).
Indian Sepoy now gets extra XP from combat (the one free promotion wasn't enough).
Polynesian Koa now has a higher combat strength (16 instead of 14).
Persian Dar-be-Mer no longer has maintenance.
I promise not to update this mod so frequently anymore! Version 7 should be the definite version (I hope).