Generally follows the same standards as their portrayal in Fate/stay night.
The near-future setting share a lot of its visual identity with EXTRA, but EXTRA is secondary to the franchise, so no need to stick to “Heroic Spirits replicated as data” in other, unrelated spin-off titles.
Servant status
Heroic Spirits will appear under one of the conditions below. More options may be invented later.
A: Heroic Spirits already existing in Servant form by the start of the game. Can be summoned from the game’s Summon menu.
B: Heroic Spirits that turn into Servants when defeated. They will appear as enemies in each story chapter and switch status to A when defeated. Consider them Servants placed under a lock due the villains tampering with history.
C: Heroic Spirits you can’t make into a Servant even when you defeat them. Bosses.
On the depiction of Noble Phantasms
If possible, I want Noble Phantasms to come locked, until they’re obtained by advancing the character-specific episodes or the main story.
Of course, I have nothing against some few Servants starting with their Noble Phantasm already usable.