I tried this once before and it never got off the ground.  The premise is you are the champions of a deity and you have been granted limited immortality. (Highlander style) The champions are out there removing other champions and by extension their deities from existence.

There was a bootleg highlander manual for 2E AD&D way back in the 90s, don't have a copy anymore were you planning to use Mythic rules?

Some advice. I would have a way to highlight the immortal part of that tale, make it stand out.  But I would be ready for those moments to be unrelated to combat.

So basically, if every fight has the immortal protagonists risking their immortality by fighting other divine emissaries who can kill them ... then it’s not really that special.

But on the flip side, some of the cool factor this premise has might fade a little if the characters run into too many ‘normal’ foes.  Winning encounters you had no chance of losing is also fraught with the not-funs.

Having the immortality matter, but matter outside of combat will be the challenge here. Like some of the stuff that made Highlander such a cool property in the first place.

Flashbacks to hundreds of years ago, meeting allies/enemies that you have hundreds of years of history with, etc.

In reply to JRScott (msg # 2):

I was planning to use the mythic tiers.  I have a pdf of the ogl d20 version that Ive taken a few things from.

Mythic is a fun twist.

I feel like I've heard the name Highlander before somewhere
Oh, also in D&D BECMI the "I" stands for "Immortals" (Though I've never actually read too much into it)
Anyway mythic pathfinder seems like a good time, so I'll stick my interest in this