More elaborate story: add globe map of locations of campaigns (Asia, Greek etc.) = consider of possibility to choose which campaigns do you want to star first. Bigger perspective of map with short cinematic at the beginning about civilization, gods etc. = initial instruction. More civilizations, more included gods with major / minor impact = potential further story. Story could be affected by myths, history. Also, add new fun fiction ideas of how characters / gods would potential continue or ends. Potentially, longer campaigns itself = minor / less quest etc.
More variety of choose between gods: in each age (custom maps, campaign, multiplayer etc. mods) = instead 2 choose between more. possibility to choose from pool of gods before e.g., multiplayer game. Richer pool of gods power = potentially to choose from!
Add “Age V” to game: I thinks it would be very good idea to add fifth age (maybe Titans age or Gods age or something like that), due to added fresh new mechanic for player! (see Titans for further explanation).
Titans: should by in my eyes mechanic only for late game, rather very late game (the most expensive, the most overpower unit in the game). Potentially used only in 5 age = very expensive to reach age V, but very rewarding = every each civilizations / gods could have very unique and overpower mechanics (unit / builds upgrades etc.) to finish your opponents, especially in the late / very late games!
Gods favor: I am toying with idea to add one maybe questionable mechanic to campaign or custom modes, that after every game you can ““earn gods favor”” for several things like: improve your army, builds etc. or maybe skill (passive or active) of your in - game or new created demigods.
Add polished, very handy editor for custom purposes!
More frequent support with DLC´s.
New variety of buildings (for example like in AOE IV landmarks) = addition special building in each age!
Add achievements by rarity. Some should be very prestigious = almost impossible to achieve! Also, those achievements should be visible on your web / in-game account and game itself! = it´s for hardcore player purpose only!
Toying with idea with in-game skin system, like for example: If you complete campaign etc. let´s say: “stole the trident” and you finish this, you will receive into the ““ARMORY”” = in my eyes it could be something like storage place where can you chose your skin on your for example hoplite and equip them with golden trident. This object should be visible in in-game main menu! → for monetization: some should be at the beginning of final version and for the future those features could coming with DLC bundles = Additional repeatability for players who already completed for example campaign mode etc. and other mods and also it´s new impulse for new players (means new skins for every parts of soldier should be constantly added to game via DLC´s or patches). → Armory should be in in-game menu!
Level in Co-op mod: Toying with idea to have some type of level of experience only in co-op mod. Could be completely disable or there should be some handicap if players wants! But, it should be completed balanced, if you e.g. playing new newbie and you are skill player.
Co-op mods: Could be something from like “Hero line war (Warcraft 3)” up to mission defending temple of Dionysus, Ra etc. = ““There are many, many ideas”” (e.g choose between only gods / demigods or civilizations). There should be difficulty in different aspect like how many players are playing, “which level do you have” (see Level in Co-op mode) etc.
Add challenges / quests: weekly challenges, or / and months challenges = reward has already been mentioned (god’s favor = could be exchangeable for example in Co-op mods.)