This is really interesting thread and I like reading everyone’s ideas. Here is what I would theorize regarding the implementation of a new “power infantry unit”.
If the new unit has similar properties to the regular militia line, such as similar speed and is exclusively melee, then I think it will see about the same amount use as the militia line regardless of any HP, Armor, Attack and attack bonuses. The same issues that create handicaps for the militia line are still going to apply in terms of utility and usefulness.
What I would recommend to enhance the current meta paradigm is to make the militia line units tech into this role of a “power infantry unit”. I would love for AOE2 to have more unit content and also would welcome a bucket load of regional units, but I don’t think the game’s design direction lends toward this type of inclusion. Take for instance AOM where the tech trees of each civ are fairly diverse. While they share similar units, you can expect each unit belonging to a culture to have unique properties that are great for specific situations. For AOE2 to lean into this type of asymmetry they would need to redesign their tech tree because each civ uses a standard unit roster. Adding new units would create problematic overlap. I think a good example of this is when they gave the Stepp Lancer as a regional unit. Each of those civs already has access to light cav. What is the inherent advantage to using this unit? Does the additional cost over light cav justify the slight differences in unit? As such I don’t think they are heavily utilized in competitive play due to not having a clear advantage. This is because AOE2’s focus was on creating unique stat buffs and changes through choice of civilization. Turks getting free light cav upgrades on the other hand is inherently beneficial and synergizes with a pre-extent unit tree and well understood unit roles. This is why I think introducing a new unit only muddies the current unit meta and creates overly specialized roles that will be hard to determine how useful they can be in practice vs. the generic militia line.
Below is a great explanation of various types of attack strategies that help in one’s understanding a unit’s particular role in the meta. Every game is unique, but these 4 basic situations are probably close to how you are going to be using your forces.
For the militia line infantry unit they seem fairly limited in terms of which types of attacks you could efficiently conduct. Maybe a power unit would fair better, but it would still struggle in some of the following scenarios.
As a raid unit they lack the speed or range to do crippling damage to an economy. Cav are fast allowing them to quickly get into unprotected areas and the range of archers allow them to pick off units. Infantry have to rely on a surprise timing that catches the defender off guard.
During a skirmish the same problems prevent them from gaining map control more efficiently than other units. Cav use speed and mobility to get the positioning that is favorable or delay until they reach a number advantage and archers can hit and run to whittle away infantry to prevent taking an unfavorable fight. The main advantage they have is their potential cost effectiveness if both sides take damage.
Assault is really where I believe they have the best utility because as you are attempting to damage infrastructure it is more likely you can encourage a favorable engagement and use the cost effectiveness to your advantage. This is still running a considerable risk if you miscalculate the opponents strength get picked off trying to slowly retreat.
Siege is pretty similar as the opponent likely has to intervene to prevent key buildings from being destroyed so you could likely take a fight on preferable terms.
Considering the assault and siege are the two most likely scenarios infantry will be effective I theorize that making the militia line more viable for these fights would be more beneficial than adding a separate unit that may detract from their usefulness, making them completely obsolete, or would overlap with another civ’s UU, making them less of a civ specific bonus.
There are also critical changes to the game that I think would improve this paradigm. The biggest problem being the associated upgrade techs for infantry. If I could rework the tech tree I would have the militia line and the knight line share common armor upgrades. Already they share the forging line, but sharing armor would allow a player to pivot more easily between cavalry and infantry. For instance, what if an infantry assault fails? Now you can rebuild with knights and not be penalized for pumping resources into infantry armor. What if your knight rush is defeated and you need to conserve resources? Now you can train infantry that retain your tech level. Additionally I would rework supplies. Knights gain improvements to speed, HP, armor and attack, while infantry gain a cost reduction in food, armor, attack and added building damage. The reduced food is economically beneficial sure, but it doesn’t improve how the unit performs in a fight. Why not instead give them a health upgrade like bloodlines and also a bonus to pierce armor? Allow them to have greater survivability while assaulting a base. This way they can lean more into an assault/siege role and have some inherent advantages over their cav and archer counterparts. Why not also buff arson to put on more pressure for the opponent to react?
Anyways, I would love to see more units and certainly would like infantry to be more viable in the current meta.