These are what I would like to see in the XP. Some of these ideas are stolen from other posts I've read, others are my own, and a lot are from civ2. (NOTE: I'm NOT going to include changes I can make myself...adjusting unit ADM, adding govs/civs/etc, I have personally made may large edits to the game rules, it is easy to do...if you don't like the move rate of ships, or the attack of tanks, or the upgradeablity of a unit - change it. For MP games it could simply be a requirement that all sides must be using the same .bic file)
BTW - I think this thread should be abandoned soon and the person keeping the list should begin a new post (posting the list). Here we could argue over what ideas we would really love and those that most of us don't want / don't care about. This way if (when

) Firaxis acts on this list, they don't spend a good deal of time and energy on something 1% of us want 50% don't want while ignoring something 50% want and 1% don't want (the other 49% would't care). (We could also figure out how to make some of the ideas work

)
FIREPOWER / HITPOINTS! My #1 problem with civ3, and the biggest case of devolution from civ2. This NEEDS to come back. Apart from its obvious advantage (fewer spearmen killing tanks), it is considerably easier to balance several units over different ages (IMO). The only remaining question is what to do with conscript / regular / veteran / elite units. One solution is a civ2 / civ3 hybrid combat system. Use the old HP/FP system, and have experience levels be multipliers to the HPs. For example a conscript would be 50%, regular would be 100%, veteran 150%, elite 200%. So envision an infantry unit with (for the sake of argument) 20 HP: A conscript would have 10HP, regular 20HP, veteran 30HP, elite 40HP. Or perhaps a tank with 30HP: conscript (if their is such a thing) 15HP, regular 30HP, veteran 45HP and elite 60HP.
I have read posts that try to get around the problem. The most common posts fall into 2 catigories:
1) Solution: simply multiply the attack by era: I have already done this, and it is still week...my 33/33 destroyer (DD) just lost last night to a 12/12 Man of War (both ships still in green).
2) Solution: in patch/XP make some units indestructable to others. For example make some system so that a spearman can't possibly hurt a tank...well I don't have a problem with spearmen "hurting" tanks -> just think of it as:
a) some tanks are killed when not in battle (sneak attack, infiltration, killing the crew and dumping axle grease into the engines and salt water/dirt in the fuel tank). The problem I have is this happening to an entire unit at the civ scale...a platoon or company perhaps, but a relatively fresh civ sized unit (brigade?) is a little hard to swallow. HP/FP would solve this.
b) the tanks must go down for servicing, resupply, crews need rest, etc. The "damage" to the tank may not be physical at all, just it needs more ammo, gas and an air filter changeout. If you run your tank too hard (attack with "damaged" units) and get killed, you ran out of gas/bullets/energy or your engines just starting crapping out (clogged with dirt), treads falling off, etc on tanks the desperately need servicing, crews/troops that need rest and weapon stocks that need resupply, and you got overrun...well by the length of time I spent on this issue, you can see how important it is too me...
BRING BACK HITPOINTS AND FIREPOWER! PLEASE! I'M ON MY KNEES BEGGING! PPPPLLLLEEEEEEEAAAAAAASSSSSSSEEEEEEEE!!!
More than anything else, FP/HP need to be brought back!
naming: Simple concept (for a simple mind) but I really want it (call it fun factor). Especially units. Ever since civ1 I've wanted to make the 82nd Airborne, 1st Cav, USS John Paul Jones and the Frink Guards. This could be optional (turn it on in preferences, or at the beginning of the game). I saw someone else mention this, so I guess I'm not the only one. How about the rest of you?
Peace conference: this idea is rather complicated, so I put it in its own thread at:
http://forums.civfanatics.com/showthread.php?s=&threadid=14024
now for the less important changes (IMO):
Food convoys... I like this one, but take it one step further, add food as an export if you have extra in your cities. Those civs in a long war with a real War weariness problem (and the starvation that comes along with it) will love you.
Republic / Democracy, why is EVERY AI civ a democracy? It would be nice if AI civs were a mix (perhaps use that civs preferred government in steady state)
Republic / Democracy, should have penalties for using captured works, razing cities, killing population (through bombardment), especially in the modern era. Civs with these governments should also look down on those engaging in such practices.
Editor: ability to set the number of resources per player (or at least a better explanation than current in the help file - so I know what one number (200?) will do when I have 8 players (2 resources per player I think). What would it do for 10 players? 3? what does raising this number do? lowering it?
AI: Upgrade units...please, after the first few rifleman, I have to kill his spearmen
Upgrade cost: right now it is dependent upon resource cost. However I lowered the cost of later units (so that new city isn't building an infantry for 80 turns (or what ever)). The problem is that now the upgrade is free.
More trouble for a civ when it loses its capital. Right now it only appears to move to another city. Perhaps a turn of anarchy, followed by communism style corruption until a [reduced fee] palace is rebuilt. However, a palace in this case could only cost a few (10, 20) resources and be able to be rushed by $$$ or population (depending on gov). This way a big civ could recover in 2 turns (1 anarchy, 1 to rebuild the reduced fee palace), while at the same time being hit harder (more corruption and such). A smaller civ may have to wait a few turns to finish the palace, but the corruption won't be as bad.
Subs- why can frigates attack subs by "accidentally" running over them. How about, if a unit can't see a sub, yet runs over one, the sub attacks it (if at war, if at peace, the surface vessel just passes over it). Example: Transport/frigate runs over sub -> resulting combat uses subs attack and transports/frigates defense: and DDs should be able to see subs.
Editor: Ability to increase range of air units / paradrops, etc to greater than 8. 8 Might be ok for a small map, but on a 256 X 256 they are nearly worthless. When you figure that stealth bombers flying out of Missouri are bombing Afghanistan, the 82nd Airborne (and 75th Ranger Regiment) can air drop (into combat, not airlift to another city) their entire force anywhere in the world flying from Pope AFB
Have a flag to not allow bombers onto aircraft carriers -> you can't fit a B-52 or a B-2 onto a CVN (and with increased range on large maps, it won't be necessary).
Have a "covert unit" flag (useful for guerillas, SpecOps, terrorists): this would work the same way as subs described above (except that no unit can see them). If an un-expecting unit enters their tile, that unit is attacked by the "covert unit" - including other covert units. these units would be invisible to enemy units and inside borders (Always hidden in their own fog of war). (you could put one on that hill next to your enemy's road and see what units pass by. These could also be "hidden nationality" units, and can thus conduct covert raids in peace time (however if you capture a city with one, the enemy will see that it was you / or make capturing cities not an option for these units). Covert Units should also be masters of retreat: They always retreat (away from roads) no matter what the difference in movement is (always retreat flag).
"Hidden Nationality" Units have a chance of being discovered. While this wouldn't matter if you attack a privateer in the middle of the ocean, when you attack with a privateer (or special ops unit) their would be a chance that the AI would see that it is you, and get ticked off. This should probably be proportional to how much damage the unit takes (killing troops may lead to a discovery of who it is, capturing and interrogating troops especially helps). For discovery to happen the non "hidden nationality" unit must win the fight (destroy in case of privateer, take the ground from covert units). If this happens their is a 25% (?/editor changable) chance of discovery.
"Hidden Nationality" units would have the option to show their flag when in a ROP agreement (and transiting through) / covert units won't attack allies (MPP, ROP) that wonder into their tile.
ROP agreement includes transiting tiles occupied by your allies, and includes the use of transportation assets (Airports, transports, etc). When a ROP is cancelled peacefully, units are returned to the nearest home territory. When a ROP is cancelled through a war (surprise attack), [regarding units in the same tile] the canceller's units attack the cancellie's units. Example: I have a ROP with the French. I can place some tanks in one/many of his cities and cancel the agreement through a surprise attack. These tanks will attack his defenders (while the defenders are stripped of walls / city size benefits). Further, any units he has in my cities are also attacked. Notice that this could backfire, if I lose the attacks in my cities...well you get the picture. Further some of the most aggressive AI civs (Zulu's) might actually try to pull this on you (very rare).
Airfields - same as in civ2, only they can also be used for airlifts and trade networks. Act as colony if outside your boards (can be taken over culturally / but if attacked...war). If taken over culturally, any units based on it will return to your nearest airbase (or city).
War weariness partially dependant on losses... I you are losing many units (especially in an offensive war) you're in trouble, however if you are rolling your enemy with few losses, your people don't really care as much.
arms dealing (unit trading...same thing). Would be nice if it worked more like civ2 -> units from any city (pick the city you want to give the unit from, or select the type of unit you want, and the AI will decide which city to give it from) as opposed to just the capital. AI civs don't like it when you deal arms to their enemies.
Variable turn deals. Default could be 20, but why not a 5 turn ROP after a way to allow you to withdraw your troops. Or maybe a 40 turn trade.
Ability to cancel deals if both sides agree. Under the trade table have the option to renegoiate a trade. If one side refuses, no deal, but if both sides agree to new terms (or just cancel the current deal), well...why not?
one sided MPP / ROP...can't tell you how many times I've wanted this. Just won a war, part of the agreement is I get a ROP and you don't. Aztecs crossing your land to attack the Germans (yet you don't care about crossing the Aztec land) sell them a one way ROP.
AI: a ROP given to an enemy is not liked and could even result in war. Above example: Germans are going to be ticked! Try to give a ROP to both - both are going to be ticked...can't please everyone, and trying tends to make more enemies than friends!
Railroads: embark and disembark I've seen ideas like giving RRs less movement bonus. Well how about make RRs act like transports (but still have the unlimited move bonus). When on a RR you must "load" a unit and you can move it. At the end of the RR journey, you must "unload" the unit. Example: Turn 1: load unit and move to front, Turn 2: unload unit and fight. This would work exactly like a sea transport, except for 3 things: First "trains" are abstract. You don't load onto a unit but rather onto a transportation network. Second the goto command would use RRs (unless the destination is 1 turn away or could be gotten to faster on foot). and third, units being transported can defend, but at reduced effectiveness (call it 50% ?). And third, the bonus isn't just a few tiles, but unlimited move once embarked.
Diplomacy: Cancel an agreement with X. I want someone to cancel a trade embargo on me or a ROP (or MPP - than attack that person after breaking his alliance) Such deals should be expensive, but possible (read affordable)
Unit animations / sounds data base...especially 19th and 20th century units (Napoleonic Infantry, Dreadnaughts (and smaller coal fired ships (Cruisers) from this era), Modern (yet not AEGIS) cruisers, guided missile destroyers (DDGs), WWII era carrier, Jet bomber, a modern Marine, Airborne, Infantry unit (big difference from WWII era units in the game now) and more
Barbarians: right now they are just warrior and horsemen. Fine for the ancient era, but after that, barbarians are worthless. How about instead of just barbarian and advanced barbarian, we have a barbarian and advanced barbarian unit for each era (Ancient, middle ages, industrial, modern)...(maybe warrior/horseman, swordsman/knight?, rifleman/cav, infantry/terrorist)
On the trade advisors screen, when you mouse over your exported/imported resources have it say not only who you sending/getting it from it to, but how many turns remaining on the trade
a resource -or- function. For example, I have iron and oil, but no coal. Why can't I build oil fired trains. Theirfor rails could require iron and (oil or coal). You could also requre techs in the or field. Tanks require oil and (rubber or synthetic rubber). Finally expand the number of possible stragetic resources (the icons limit us to default+2), and the number of resources required to build something. For example 2 columns of 5 (the second column would be for the or): Example:
Tank
iron
coal // note: to make steal
oil
rubber synthetic rubber
none
civil wars...perhaps instead of the high corruption in far away cities [on that 2nd or 3rd landmass you settled] decide they want to be their own civ... civil war, some cities go his way, some go yours, and both want all of them [just in a contested region]. American Revolution!