I would definitely want to see unique religious buildings and unique religious mechanics in new AoE game unlike AoE2 and AoE3
For example lets take Islam for Delhi Sultanate and future arabian civs and may be Turks that had settled to Anatolia:
And I would want to see preferences about religions like Delhi Sultanate can choose either Islam or Hinduism depending on the play style.
ALL QUANTITIES ARE ARRANGED ACCORDING TO THE AOE2 ,ANY AOE3 PLAYER COULD FIND THE QUANTITIES WEIRD
Masjid: 75 wood , Unique feudal age religious building. Can train Imams. Masjid provides 5 population
(Masjid is a religious building that works like a school and religious place at the same time)
Imam: 70 gold, can convert enemies and Imams decrease research times by %5 percent (can be stackable up to %50, 10 imam is the limit of this aura). Train limit is 1 for each masjid and 2 for each Mosque.)
(Historical referrence about the Imams’ studying and teaching at the Masjids science combined with religion)
Sehid: Unique Islamic troop, Can’t be trained, only can be called by Jihad from the Mosque.
(Sehid means the man had died on the Jihad)
Mosque: 200 wood 100 stone ,Unique castle age religious building. Only can build one by each town center. And contains unique upgrades. And can train Imams.
Jihad: 600 food , Unique Mosque upgrade, Starts a Jihad and immediately after the research time creates 5 Sehid for each Religious building, 1 Sehid for each House
Sultanate: 500 food 500 wood , Unique Mosque upgrade, All gold income %20 faster from now on.
Golden Age: 300 gold , Unique Mosque upgrade , All researchs cost the half of the price
(Also historical referrence to the Islamic golden age that is occured between 8th and 14th century by the Islamic Alim’s such as Ibni Sina, Ibni Heysem, Omar Khayyam for more introduction about this age: Islamic Golden Age - Wikipedia )
Thoose are just mine version of unique religions system on AoE2 that could be adapted to the AoE4 easily
And there could be other many religion options like
Wouldnt be awesome to see bridges in the game??? I hear you saying yes because it would be awesome. We already saw bridges in the campaigns and scenario editor in the other AoE games but what would happen if we were able to build them by ourselves in normal games? Thoose bridges could be built like walls in the game and thoose bridges would be awesome strategic zones in the game. PLS DO THAT PLS
3.) Better Battle Formations
We saw charge mechanic of Cavs in the AoE4 fan preview but there has to be other mechanics like Phalanx formation (this has to be included because there is charge and there has to be counter of charge with phalanx) for Melee Infantry and like Testudo ( I KNOW THERE ISNT ROME IN THE GAME BUT THIS IS A GREAT EXAMPLE LOL). You could click on a special button and all selected troops would make a battle formation.
And may be pincer movement that was done by Mongols in the History (aka Turan Tactic)
4.) Morale System
Morale system is a simple one. Any surrounded troop will have debuffs for example if 5 pikemens are surrounded by 8-9 knights (even though pikemens are counter of knights) , knights will have better fight against them by resource
edits: grammar corrections im not native