The amounts of different strategies in each Aoe4 civ doesn’t seem to be that big. Many times the landmark choices are the same, with other landmarks being situational or useless. The unique techs often suggest a limited amount of viable and strong strategies for each civ, while not excelling in the other options. You still have the counter system where going for spears against cavalry (as of the latest update) seems worth it even if your civ doesn’t specialize in them, the same can be said with crossbows and archers. Going for specific counters and unique units and techs isn’t enough to make each game unique, it’s at a very similar level to Aoe2 strategy and very, very far from the amount of strategies you can go for in Aoe3 because of the complex deck and shipment system. And that’s the base of what I’m going to suggest to add more depth to Aoe4 strategy making.
I think that something like the deck system in Aoe3 doesn’t fit in Aoe4, but i think that there could be a similar but simpler approach that gives each player something to prepare before the match starts that can also add active decision making during the game without being too complex.
My idea is a Policy system. Each civ would have 15 different Policies (or more, but always multiples of 3), 5 for Feudal, 5 for Castle and 5 for Imperial age, basically un third of all options per age other than dark age. You have to choose 3 per age similar to Aoe3 deck system. Differently to Aoe3 these policies are toggles that give buffs or abilities while active, they aren’t unit or food shipments. You only have one Policy active from each age at a time, and switching between policies from the same age takes 20 to 30 seconds.
You unlock your Feudal age policies when building your first blacksmith or market, the Castle age ones are unlocked with monasteries or keeps, and the Imperial age ones with the university. This would slow down any fast castle/imperial strat, and slow any eco/military spike from the benefits of Policies. If this is too much, it could be that policies are unlocked after 30 seconds upon aging up, but i prefer the other version so some landmarks that act as blacksmith, market or monastery have the extra benefit of immediately granting policies.
Of curse I consider something like this could be added in a very long time, like 2 or more years to revive the game. It’s definitely not a priority to add a new layer of complexity to the game, first there must be bug fixing, balance changes, performance, scenario editor, modding, matchmaking, QoL features, better UI, etc.
Some ideas I have are (consider balance and tech changes in addition to make these viable, ideas and numbers are just examples) :
HRE:
Age 2: Policy 1: add an extra 10% to prelate blessing. P2: villagers construct 20% faster (not landmarks) P3: Mills, lumber and mining camps work 25% faster. P4: prelate moves 20% faster. P5: barracks work 25% faster.
Age 3: P1: emergency repairs cooldown reduced by 33%. P2: increase cavalry armor by 1/1. P3: infantry moves 15% faster. P4: gives man at arms the active ability to dodge by 50% arrows/bolts while moving 10% slower and incapable of attacking. P5: barracks units are 15% cheaper.
Age 4: P1: relics generate 20% more resources (consider balance). P2: relics provide more benefits when garrisoned in defensive buildings (forgot the numbers). P3: prelates give 10% more attack when blessing military units. P4: landschneckt has +20 health. P5: emergency repairs works 30% faster
Chinese:
Age 2: P1: Imperial officers gather +15 extra gold and move 20% faster. P2: Imperial palace Influence area increased by 1 tile, Barbican of the sun +2 range and LOS. P3: non gunpowder archery range units have +1 range. P4: maintain of Tang dynasty bonus. P5: Docks work 20% faster
Age 3: P1: maintain 50% of Song dynasty bonus if achieved. P2: Secondary landmarks 15% reduced cost. P3: palace guards and spearmen have +1 pierce armor. P4: defensive buildings have 33% more health. P5: fire lancers and horsemen have +4 damage vs heavy armor.
Age 4: P1: unique units are 10% cheaper. P2: ranged units on walls deal 10% more damage. P3: Maintain Yuan dynasty bonus. P4: All military buildings work 10% faster. P5: gunpowder units +1/1 armor
Rus:
Age 2: P1: change 50% of gold bounty bonus to food (or wood). P2: Hunting cabins generate 10% more gold. P3: Unique buildings and docks are built 30% faster. P4: wooden fortresses have +10% health and and provide an extra 5% to their bonus to lumber camps. P5: Stable works 10% faster.
Age 3: P1: Stable units 5% cheaper and horse archers gain 5 health. P2: Warrior monks have +2 attack and +1/1 armor. P3: 50% of emplacements stone cost changes to wood. P4: Warrior monks heal 20% faster and increase Saints blessing armor by 1P5: hunting cabins trickle cooldown reduced by 3 seconds.
Age 4: P1: techs that benefit siege are researched 20% faster. P2: Horsemen have 3 more damage vs ranged. P3: Streltsy can attack while moving for 1 second after leaving their
Static Deployment ability (must have at least 2 stacks). P4: One of High armory techs. P5: infantry can repair defenses (seems buggy but it’s an idea)
I could keep adding ideas for the other civs but I think I already made clear of what this idea consists in.