Even a blind bat sees there is serious problems in overall war mechanics in game. Wall seems to get most heat because it expensive to build and does.. well nothing. Also battle bonus buildings like steele, Temazcal and so on.. Their effect awhile noticeable. They are more Mid/late game buildings. Meaning a lot of newbies dont even get to build their towns full or learn anything about them. Lastly there is win or die mentality after your account is over 5 million points. Armies grow so big that rebuilding them is colossal task.. There is absolutely no point in that and thus we have an problem. Thus we have several problems that lead to fast dying servers.
Army limitations and construction costs?
For the most part corn is only limitation for troops. How far you can move them and how far you can attack with them. In some sense how many you can have. Since corn consumption is also an issue. Thus most players go straight to building eagles and jaguars. Because in late game owning anything else is pointless. For that reason I would weaken all units above bowmen and make them cheaper. MUCH weaker and cheaper. After that rebuilding units is much more reasonable.
As for limitations. Corn would still be main focus, but I would also add few more.
Population: All excess population in towns should go to global population pool. More troops you build. More global population you use. Use of global population is shared evenly in all your towns. Bowmen, EK and Lancers should be most POP/Strength or Stamina effective. If town has global 0 population it cannot be used in troop building. But it can build buildings with local population. If global population is 0 no buildings or techs can be build. Exception is Sun temple.
Population increases should be evened/lowered more and sun temple in later levels made more expensive.
Movement type: Units in attack should use more corn than those that defend. This should also vary between unit types. For instance atlants should be the same in attack and in defense. Awhile Eagles and Jaguars are cheaper in attack, Thus if you build bowmen heavy turtle account. Using it in attack is very hard. But to crack bowmen turtle you may need more players than one. EK could become unmovable unit unless its Bacabs crystal event.
First building bonus would start from production speed bonus from sun temple. That bonus is 100%. When you build Pyramid, Temazcal or Quipu house you can start adjusting that bonus. These buildings should also be more accessible and cheaper. Bigger the building higher max bonus you can get from that building. Steele stays as it is..
Wall is another bonus building every 5 lvls of wall can give 2% stamina bonus to defending troops and 2% to wall. On top of that when wall is fighting alone it has to be defeated in 1 round. Only when there are troops behind the wall fights last 5 rounds. Wall stamina should also increase 3x higher from now.
Spies fight without wall or other troop types. When spies fight defender gets no casualties. Less damage attacker gets more info its possible to get. Espionage tech helps spies to be stronger. If attacker loses all units. There is no info to get. More spies attacker sends. Better the results.
100% for Spies and 75% should be default in game. If attacker is much larger. Defender could get 100% for units too.