My opinion is that you people are not thinking ouside the box(or even towards the box's edges).For sure it will have WW1 and 2 but i think that it should include the american civil war and the spanish american war.I believe this should be a nesessity considering it starts excacly where aoe3 left off.but firts lets start with new rules and resources.
1st:The new resources should be,steel,food, currency(money),and munitions(the soldiers obviously need ammo.
2nd:the resources should be brought in by vehicles ex.civil war should have trains spanish american should have trains to trucks WW1 trucks and airplanes WW2 trucks,airplanes,and airdrops.it costs a small amount of fuel for trucks,and for the vehicle itself,but slower.airplanes are more expensive more fuel(thus higher cost)and need an airport,but are much faster and can carry greater loads.airdrops cost the same as and airplane and have the same speed ,but have greater fuel costs(due to them have to go there and back without stopping)they also have the same load capacity,but they can drop supplies anywhere on the map(very useful if fighting away from your home base)
The supply vehicles are assumed to come from your home base.
3rd:TROOPS:I believe instead of clicking on the barracks to make troops(which is just toooo unrealistic)you should have propaganda that advertises your campaign.The propaganda also costs money (obviously).each item of propaganda that you buy will "cetch someone's eye"(someone will see the ad and decide they want to join) once every (certain amount of seconds/minutes)once that happens they new recruits will load on a supply vehicle(once thier numbers reach you specified amount)and will arrive with your next supply convoy.from there they will go to the baracks where they will recieve training for whatever role you wish to put them in(rifleman gunner tank crewman engineer ect.They will after training recieve their ammunition(specified by you before the match)///go to their vehicle.you would also have to pay the troops 10 currency,and 10 food each every 10 minutes.all units will have moral(it will be shown under the health bar).moral goes away if the unit is pinned surrounded is running out of ammo or are being destroyed.depending on the situation they will run, surrender,or will have decreased accuracy.
4th:instead of villagers and civilians you will have engineers and workers(engineers are like enhanced workers,because they carry guns,and can repair some vehicles,depending on what destroyed it.engineers can also create barbed wire mines and various other explosive devises such as c4.
5th:all resources must have a warehouse to hold them.warehouses can also create trucks that can carry resources and/or troops quickly to the front lines.
6th:I think the civilisations should be these
Russia:russia should have the ability to conscript soldiers(force them into the army),but all conscripted troops will have lower moral are less accurate can't be put into special roles(pilot sailor AA gunner ,and engineer and sniper.They will also have the 2nd best tank in the game,and the best snipers.all units have lower moral.secret police.
U.S:will have commandos(they are stealthy good at close combat and have extremely high moral)shermans are the cheapest and fastest tanks in the game.they also will have one of the best infantry marines.
U.K:They will have the best overall tank(speed armor gun)and their soldiers have a fifty percent chance of detecting mines close by to them.Have the option to create sherman tanks as well.
Germany:Most powerful tank and 3rd and fourth most powerful tanks.S.S troops have better weapons moral and increased toughness and accuracy.2nd best snipers.AA guns can be converted to AT guns and artillary.U-Boats.blitzkrieg(units are 10 percent faster)
Italy:4 machineguns on their tanks.facism(increased moral,more recruits will join army).
france:french foriegn legion(super soldiers,best troops in game)magniot line(have tougher buildings).allies(at any time they chose belgium allies will arrive with the next supply vehicle fully trianed and with ammo).
finland:winter war,(They recieve no moral or movement penalty in snowy terrain and also recieve a slight protection when it snows and no accuracy penelty).allies(at anytime they may chose to call upon british reinforcements).
7th:weather and terrain play an important role in combat thus here should be the weather and it's effects.snow:slight decrease in accuracy and sight(if there is just snow on the ground these modifiers are taken away)decrease in movement and lower moral.rain:slows you down after rain(mud)decrease in visibility and accuracy while raining.windy:slight decrease in accuracy at LONG ranges.Hills/mountains:easy to defend and hard to attack,increased visibility the higher you are,can't build on uneven terrain hard to clamber up.forrests and jungles:decreased visibility.
sorry it was long hope you enjoyed it.