I browsed the new features of the Civ5 game in development and I like what I see so far.
SOME of my long-standing wish list items (as a result of long hours playing Civ4) are included, it appears, but I'll still include them in my list below just to show some areas where Civ4 has always needed improvement:
1. Borders should be negotiated by treaty. This has throughout history always been the main topic of inter-civilization negotiations, quibbling over acres of land. Kings never sat down and argued over handing over technology secrets most of the time, it was about LAND. That's absent in Civs 1 through 4 and would be a remarkable coup to add it in Civ5 (if there's still time?)
2. Technology "leaks", not only through spies, but simply living next to a high-tech civ should at least give a neighbor some points or added bonus of research rate towards those techs. In reality that's how technology has always spread: guy shows up at a village with a new steel sword, and the locals say "gee that looks fine, how do you make a sword like that?" If they're lucky he's a blacksmith and "for a price" is willing to show them how. It spreads from that village to the next, and so on. I'd even go so far as to say that one half or more of a civilization's technology should get leaked into it via "general spread" rather than some leader decided "we need to research that".
3. Siege weapons are ranged weapons. They should behave the same as bombers do in BTS, just with a shorter range than bombers, and can only be "intercepted" by cavalry (when tech levels are compatible, that is, a primitive cavalry unit shouldn't be able to intercept a modern mobile artillery no matter how hard they charge!)
4. It would be super-fun to have a split between a campaign level screen (the traditional Civ map) and a tactical level screen that you go into when a battle takes place (similar concept to Medieval Total War). And on top of this have a fun little romp routine (not unlike Grand Theft Auto) when "sacking" a city (although in the modern era that would cost unhappy citizens due to "the world considers you a villain!", in which case you'd probably want to "treat the citizens professionally" or some such, no more rape-and-pillage, get that out of your system in medieval times!)
5. Players shouldn't have to design their own mods or learn Python to make realistic scenarios from times in actual earth history, e.g., the Norman Conquest of Britain. At the very least there should be a custom scenario that starts with the actual earth map and lets the player choose which civs start where on that map.
6. New resources:
a) Yarrow -- required for Longbowmen
b) Tobacco -- 2 happy, 1 unhealthy
c) (change) Sugar -- 2 happy, 1 unhealthy
d) Tin -- 1 hammer, required with copper (bronze) for Axemen; 1 happy with Forge (pewter ware)
e) Rubber (special plantation, requires Chemistry) -- 1 hammer, +100% road movement after Combustion
f) Natural Gas -- 1 hammer, removes unhealthy penalty from coal and oil in factories, etc. ("alternative" energy source)
g) Wood as a resource -- 1 hammer, required for all wood-based units (catapults, trebuchets, wood ships, etc.), requires forest and a road; as with other resources, can (must) be traded for by civs lacking any wood or that have chopped away all their forest.
h) "Recreational drugs" (coca, hashish, etc.) -- 1 happy, 2 unhealthy
i) "Psychedelic drugs" (mushrooms, etc.) --+3 GPPs for Great Prophet, increased risk of "accident" events (e.g., forge fires)
j) Tea (plantation) -- 1 happy
k) Cherries (plantation) -- general non-tropical fruit resource analogous to "bananas" in jungle areas, 1 healthy
j) Chickens (coop, req. Animal Husbandry) -- 1 healthy, food value similar to Sheep
7. Unique National Wonders (some examples):
a) Egyptian, The Great Pyramid (no longer "world" wonder), enables all ECONOMY civics (instead of government, which would be an imbalanced overpower for Egyptian civs)
b) English, London Bridge (2 free Engineers in city)
c) American, Route 66 (+100% road/rail travel on continent)
d) French, Arc de Triomphe (-75% war weariness)
e) Mongols, Tatu Aqueduct (+2 food, +2 healthy, all cities on continent)
f) Chinese, Great Wall (of course)
...etc.
In fact the concept of a "world" wonder shouldn't really be a named wonder from known earth history, but rather generic Wonders that open up with each new technology, e.g., Great Archery wonder at Archery, archery units +2 XP... etc. The named wonders should all be unique to a nation for a realistic feel (no more of this "Eiffel Tower of Moscow" crappola!)
8) Some more particularly "world war I" era units:
a) "Doughboy" (between Rifleman and Infantry in strength, etc., let them wear a "Smokey the Bear" style campaign hat or perhaps different graphics based on the nation)
b) "Machine Gun Tank" (Infantry strength + about 2, +100% versus Machine Guns, same movement as Doughboys)
c) "Heavy Cavalry" (like a mobile Doughboy)
d) workers can build "Trench" (like a fortress but more defensive bonus)
e) "Tank Trap" (stationary unit built by workers, tanks cannot pass)
f) "Combat Engineer" (can blow up Tank Traps, sap Trenches, etc.)
g) "Biplane" (half the range and strength of Fighter, similar in other respects, requires Flight; newer Fighters and Bombers both require Radio)
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Things I do like about Civ4 that I hope don't change (too much) are:
1) The economy engine in general, completely owns
2) AI predictability (lol, gotta give us weak-minded humans SOME advantage now!)
3) Movies for the wonders are generally stellar, like the style
4) Graphics in general are pretty good although I also like the Civ5 screenshots
5) LOVE those paratroopers!
(end on a positive note, right?)