I would've just gone with "Heretic" or "The Heretic." Much more memorable.
You would have gotten a letter from Raven's, id's, Bethesda's, Activision's, so in the end MS's lawyers.
So probably not as memorable as you think, if you forgot that there were already two Heretics.
It follows the Uncharted name scheme:
Series Title: Uncharted
Entry Title: Drake's Fortune, Among Thieves, Drake's Deception, A Thief's End
Horizon, too with Zero Dawn and Forbidden West being the entry titles.
Question is is Intergalactic the series name?
Makes sense. Not feeling it though. Intergalactic and Heretic are both just too unusual in everyday use and feels automatically pretentious. Maybe would need a trailer to associate some actual visuals with these words. Did not feel it with Horizon though either, while its first trailer was great.
Not super important anyway, but I guess the good simple names are already taken, so everyone comes up with convoluted word salads.