It would be nice if the following features were implemented:
1. Scorched earth policy - easy ability to destroy own tile improvements & demolish buildings (I know that the later is possible though. The only problem with that is that there is no use for it in terms of scorched earth policy, as when the city is captured, the one who captured it has to rebuild EVERYTHING (as if it was demolished) and that's just sily. It brings me to #2)
2. Change the way capturing cities works in terms of buildings. When a city is captured, the one who captured it should not rbuild all buildings unless they were purposefully demolished by the original owner. To make a cpature more realistic, however some building should be destroyed (especially if artillery/bombardment was used), however some should remain. Otherwise there is not too much sense in capturing and keeping the city...
3. This a rather huge request: I think more techs and more various units should be added. For instance from the current vanilla game and most of the mods I personally did not get a good feeling in terms of progression through history with units. In my opinion it should be like this: warrior/hunter(missile)/sp/ancient spearman -> sowrdsman/axeman/improved spearman/archer/skirmisher/chariot & horse archer (now mounted unit type becomes available due to domestication) -> phalanx/hoplite/hyspast..(sorry never remembered how to spelled it correctly)/juveline/cavalry (not to confuse with gunpowder one)/battering ram (this is probably a good place to introduce seige weapons unit type, battering ram should only be used on cities bomardment, i.e. it cannot attack) - the theme for this age is Greek -> legion/praetorian/+improvements to archers, mounted, and skirmisher units & also introduction of advanced seige weapons (catapult, balista) - this is the Roamn age -> finally we are moving into dark ages -> then to middle ages -> reneissance & exploration & later (first musketteers begin introfuced, conquistador (should get big bonses vs native american units of that time), etc) -> enlightement & into Napoleonic Era (riflemen, calavlry, advanced acnons & other bomb. weapions of that time) -> industrial era (first World War) -> infantry, artillery, advanced gunpowder cavalry, first tanks, biplanes -> World War II - type units -> Cold War-type units -> Modern units -> future units
These are definitive ages from the military perspective. Some of this is already implemented in some mods, however not in as much detail. In particular there's no distinction between early egyptian & babilonian vs greek-style vs roman style eras (its all just one in current versions), also there's no distinction between early & late medieval, there are not that many exploration & enlightment age units, napoleonic times are also lacking - basically just rifleman is clearly not enough, - in fact at that time there were first air baloones made, so theoretically that unit could become available - only for survelence (not bombing) purposes.
Another point to make here is that I think hit points should be altered. Generally they should be extended to around 90 for modern units and up to may be 300 for futuristic units:
warrior = 2
archer = 4
swordsman = 6
phalanx = 9 + strong defence bonuses
legion = 12-13 + offence bonuses
longbowman = 18
maceman = 18
knight = 22
musketman = 25
conquistador = 28
rifleman = 35
infantry = 45
mechnized infantry = 60
IFV = 75
modern armor = 85-90
the above are just proposed values, and by all means they should be refined with certain bonuses and promotions)
also I have trouble with modern era navy: how come destroyers cant attack several times per turn - I think it's just natiural to think that a single destroyer should defeat say 4 galleys nopt just strength-vise but also turn-vise. Same goes for IFV and several other modern units.
AS to the navy, I think ancient navy should do much better - not just galley, but also trireme, quadrireme, etc...
The number of technologies should be increased as well.
4. It seems strange to me that future tech gives just +1 happiness and health - it's a layman's approach. I think there should be more variation - like may be every 5 future techs one hammer is added to every tile or unit cost reduced, or whatever...
5. This is big... You CAN carry over research points to a new tech, however this logic surprisingly does not extend to production...
In some cases you can have the following situation: city production per turn = say 200 hammers, unit cost = 70 hammers => result = waste of 130 hammers -> wrong This is what should happen i think:
Case 1: units: - produce (city production MOD unit cost) units & carry the remainder to the next thing in que: 200 mod 70 = 2 + 60 hammers carried towards next thing => yes 2 items should be produced, or whatever quantity in your case
Case 2: buildings/wonders/projects: obviously you can't have 2 granaries, so show a poup -> the one where you select what to rpoduce next, and just copy the remainder of hammers (city production per turn - completed building cost = remainder) to the neweley selected item (if it's a unit whose cost is still less than a remainder (your city is a production monster) -> then do as in case 1 -> produce more than one unit), if a the next selected item is building start priducting it, carring over the hammers to it (if the cost of it is less than available carried over hammers, then start from the beginning - offer second choose what to build poup, etc...untill the remainder of hammers is exhausted.
I know that what I wrote above is not easy to implement to say the least, but these are just some ideas that I have been playing.
I think Civ IV in terms of technology is a great foundation, however in terms of gameplay soooo many things still need to be done. What I have listed above is just a fraction of it. Howver I hope that in a year or may be more we will see such trully great mod packs.