Well if I had of won that 600 million powerball I would have donated [/Dr. Evil voice on]1 MILLION DOLLARS![/Dr. Evil voice off] for a kick started to THIS expansion. (since I didn't I will type out this wishlist, although nothing will come of it)
Major focuses
1. Overhaul Diplomacy and faction interaction: I think that SMAC from 1999 actually has the best diplomacy I have found in any strategy game. Granted it had weaknesses and flaws and could use advancements from the past 14 years, but it would be a good starting point. Some of advancements I would suggest:
Lend gold (gildar?); gift and or trade trained units (hell even heros); coordinate attack plans with allies; co-ordinate research;Multi-faction pacts (like teams but it could be formed and broken during the game); have trade treaties set up caravans from each level 3(maybe 2) level city in your faction; joint victories; have leaders surrender and their faction becomes a submissive vassal instead ; maybe joint quests (you are Lord Relias and you must work with Queen P. to kill a dragon...so it would require 3 factions in battle, yours hers and the enemy); etc.; wtc.
2. More in depth quests/roleplaying:
This needs far larger tactical maps, the ability for more enemies to appear after killing what is on the map, and the ability to interact with objects/people on the tactical map. Like for example, move to the center of a large map and seize an objective, then hold it for 10 turns while a troll army attacks you. Everytime you kill a troll a new troll appears. Attack a group of bandits, and once you kill all but the bandit king, he asks for mercy and offers to pay you 500 gildar. If you say yes he escapes. If not he calls in reinforcements.
Additionally, on the main map have more quests with choices and multiple tasks. For example. You go to a goodie hut, and you find a lost princess. You can choose to A. Take her back to her father. He gives you a nice reward. end of quest. You ransom her off to slavers. They give you a better reward. This creates a goodie hut on the map, and when you enter it you are attacked by troops/assassins sent by the princess's father as payback. After defeating them you can either go back and rescue the princess from the slavers, or wipe out her father, either way end of quest. You can feed her to a dragon. The dragon will then grant you one request. You can tell him to fly away or attack a city of your choice. If he flies away a goodie hut/dragons appears on the map, a few turns later and it is a far more powerful dragon demanding a princess. You can appease him, or fight him off. If you are an empire you can sacrifice the girl at a death shard with a shrine, and you get a powerful demon ally. Again her father will seek retribution and you can either kill him or somehow atone. If you are a kingdom, you can take her to a life shard with a shrine and she will become a henchman with healing abilities. You can then use her to recruit her father via a quest as a henchman with command or have him found a pairden(sp?) temple in honor of his daughter.
3. Going hand in hand with the previous suggestion. Each hero come with an individual quest chain. (his idea is a ripoff from another suggestion in the forum, but I forgot who made it. Sorry. However keep reading for my twist) By completing the chain you gain their loyalty (similar to Mass Effect 2) and once loyal they gain a worthwhile special ability/item/potion/artifact. The artifact might be King such and such's Royal Scepter and it decreases your unrest caused by number of cities by half in all of your cities if your sovereign equips it. etc. etc.
4. Minor civs/minor wildlands + Far harder to clear wild lands:
There would be a large number of one city kingdoms that have less tech, a much slower growth rate, possibly no pioneers, etc. Although weaker than normal kingdoms or empires, they could be trading partners, client states; or if allowed the chance to grow; possibly even critical allies later on in the game. A few would be present at the start of the game, and as inhabitable areas get cleared of monsters, but not settled later in the game, more would pop up.
For the minor wildlands, they would have a number of lairs 2-5 of either the same or similar or allied type of monsters, and they would generate units more frequently. There would be lots of these spread around the map, overlaid on normal territory. So once cleared, it might still be an unsettleable waste instead of a bonanza of great places to settle like current wildlands. However, when you cleared a lair on either minor or normal lairs, you would get fame, but instead of disappearing lairs would become in active. Once a player/AI had inactivated all of the lairs then (for a minor wildland) and completed whatever other objects (for normal wildlands) then the wildland would disappear. If however, there were three wildling lairs in a minor wildland, and you only clear two, before your army leaves or the wildlings kill it, then a wildling can reactivate the lairs by occupying them. Same would go for current wild lands. So it might take multiple armies making multiple excursions before a player could clear a major wildland.
5. Anti-steam roller traps.
First, import the partisans idea from civ2. You conquer a city and it loses some population who becomes a wandering militia/bandit army close to the city after the city falls. It doesn't always happen the exact turn you occupy a city. The unrest penalty for conquering a city is 100, and every turn a city is over 100 (because of tax rate unrest and city number unrest it has a high percentage of generating rebels (33%? 40%? 50%?). However, even friendly cities can generate rebels. High unrest (75%/80%-100%) have a moderate chance of creating rebels (10%? 15%? 20%?) Moderate unrest cities (40%/50% - 75%/80%) have a low chance (2%? 4%? 8%?) of generating rebels.
Secondly, make razing cities cause a far larger diplomatic hit to both the factions you raze and everyone else, but at a lesser rate than them. Evil acts could have a temporary unrest penalty. Like for example you could raise a city, but it would add 5 or 10 unrest to all the cities in your empire and would decrease at 1 unrest point per turn. Backstabbing a longtime ally, could cause a significant hit to unrest, like maybe 25 unrest, which also decreases at one per turn. So if you backstabbed a trusted ally, and raised his cities, then suddenly you might start facing rebels, and have highly unproductive cities. Obviously slave lords wouldn't receive an unrest penalty for razing cities, and betrayers wouldn't get a penalty for breaking alliances etc.
Next, the possibility of heroes which you haven't completed their loyalty quest to rebel and become an independent unit hostile to you on the map. All of their army would go with them.
Better city militias. A million ideas out there how to do this. Implement some of them. My favorite would be city militias would have unit sized tied to city levels. a Level 5 city have 6 person groups, level 4 has 5 person groups, level 3 has 4 person groups, levels 1 and 2 have three person groups like the current system.
6. Bug fixes, balance improvements, and more polish. Basically in addition to the big things, all of the little improvements that happened during the LH beta.
7. Stretch goal 1. As stated above faction differentation.
8. Stretch goal 2. Bring back an improved dynasty system AKA a mild Crusader Kings II ripoff meets game of thrones when it comes to hero and heir management subgame
9. Stretch goal 3. A more dynamic world. Seasons with graphical and gameplay effects. Non random recurring events - aka. festivals (in fall there might be a harvest fest in a city with a farm etc. etc) , ceremonies, more neutral or beneficial entities on the map outside of goodie huts to interact with. Basically some deterministic extra rules that would partially occupy the gameplay flavor niche occupied by random events
Also, expansion or not implement more DLC. I will buy this stuff.