If a hack includes extremely powerful characters in its narrative how can you properly implement them in gameplay without compromising design and difficulty, especially when playable?
With enemies it seems easy. An overpowered enemy is usually not meant to be killed but avoided, making it more of a map element.
Depends on what context they’re OP in.
If it’s near the endgame, just go the Gotoh route and drop them in as-is, might as well give the player an anti-softlock tool or just have the fun of a strong free endgame unit.
If it’s near the beginning to middle, you could go the Black Knight route and only have them around for one or two maps where they are a crutch for your growing army. (Coming back later is optional and depends on the plot)
Maps with split deployment are an easy answer, if you really need this character to be playable rather than being an NPC. Have them be force deployed in some separate area of the map designed around them, while your regular units handle the more normal areas of the map.
I would simply allow them to be overpowered, I am of the belief that Fire Emblem design is an interplay between strategy and narrative. Allowing a unit to be so much above other units reinforces the narrative aspect of the game while also allowing for interesting gameplay situations. There’s a lot to be said about letting the player feel powerful.
There’s a reason why Camilla’s such a liked unit even by those who have such a disinterest in the character themselves that they don’t even bother to read into the character.
Try allowing for the player to have a very powerful unit and see how it feels, there’s no real design decision that I would say cannot work in any context and saying otherwise to newer romhackers is kind of senseless.
I think it depends on what game you want to make.
If you want to make a more “casual” game or one where story is more important then gameplay giving a strong unit early is fine.
If you want a tight gameplay experience than aside not implementing the character placing some restrictions on the unit is preferable, such as skills that prevent certain actions, locking them out of certain items, giving them bad weapons, or limiting availability like SmeargleDBZ said.
If you want something in between the two extremes use less strict restrictions, that fit the game feel you want.
I also agree with KrashBoomBang’s ideas making units take on separate objectives also makes for more unique maps.
Something I want to say is that though Camila is very strong she’s still mortal, which is something to keep in mind you can have strong units that are still liable to die.
I would just not write a narrative that requires such a powerful and centralising unit to be available, ideally.
But as Krash says, you can just give that powerful unit one particular job on the map to do and the remainder of the map be reserved for other units.
You can also use terrain to discourage the use of that particular unit. Maybe you have a powerful unit like Perceval available but the next map has deep sand that restricts his movement. He will still feel very powerful because his other stats plainly appear to be so but he won’t be able to overshadow weaker units in this context.