Example: You're playing as one of the Elven races, which get Swordsmen as their T2 mêlée unit, but you acquire a Dwarven Warrior that you would like to upgrade along the mêlée line. Because your Barracks are able to produce Elven Swordsmen, your Dwarven Warrior would normally only be able to upgrade to a Swordsman, which is a Human Swordsman in appearance, although they retain the Dwarf racial promotion. They can then be promoted to Champion, which does switch over to a Dwarven Champion appearance (very sweet look, BTW).
What I would like to see is if units that are of a different race than the owning Civ, are upgraded in the Civ's cities, they upgrade into a form that retains their racial appearance. Where this gets tricky is when:
- You have a Civ that would have a (not normally racially variegated) UU or variant (Swordsman/Axeman) on that upgrade path,
- Your Civ doesn't normally upgrade units of that type (or the reverse, like Clan Warriors can't upgrade to Champions, but I had a captured Orc Warrior become a Champion with my Elven Civ),
- The acquired unit would normally upgrade into a UU or variant on its original upgrade path, or
- The acquired unit is already a UU.
The first is an art asset nightmare, but would of course be fun to have. The second point (first part) is tricky if the Civ can't build the particular upgrade building (unless it would default to either a different building or just be territorially available, like some existing upgrades). The other part has obviously been done in the past, but I don't know how completely it's been implemented.
The third point is a little more of a "too bad" issue for UU's only, because if the unit doesn't have access to the old Civ's resources, it probably shouldn't be able to upgrade to the old Civ's UU's. Variants are a different matter, more in line with the reverse of point #2.
And the fourth point is more a question of making sure it doesn't lose its previous "uniqueness" if you upgrade it. This might not be possible to carry everything that was special about the previous unit, especially if it is different in a core ability (Strength, Movement), unless they are set up as promotions versus core changes. But again that may just be the cost of having a unit that is not of your Civ.
Civ to Civ upgrade changes are handy, but it would also be nice to be able to upgrade Goblin Archers and other such Civ-less units. I know I'm able to upgrade Barbarian Lizardmen into Rangers and such, but they of course switch over to Human graphics usually.
All told, it's a lot to ask for, but some of the individual items may be small enough to qualify for this thread.