A villain that has a certain connection to a particular hero or heroes and therefore wishes to do them the most harm/stop them, and vice versa.
Technically a Nemesis would simply be a particularly passionate and difficult rival who is determined to bring about your demise.
I believe in this game the Nemesis status is decided thematically (through background story) and then an additional game mechanic (the +1 damage modifier) is added to the villain/hero combo to represent that Nemesis status. I don't think there is anything else mechanically that indicates that relationship. Which is why I am excited to see some kind of built-in rivalry put into the Vengeful Five deck mechanics.
I always considered the Nemesis status in the game as a comic book reference : the nemesis of a hero is the villain he always finds on his path, sooner or later, the one that the readers would immediately think of when thinking about the hero. Legacy fought dozens of villains, but the one everyone associates with him is Baron Blade. But I tend to see the game as meant to be an "adaptation" of the comic books. Except that the books don't exist :)
Nemesis (mythology), in Greek mythology, a spirit of divine retribution against those who succumb to hubris. - WIkipedia
"Do you know what "nemesis" means? A righteous infliction of retribution manifested by an appropriate agent. Personified in this case by an 'orrible c**t... me." - Bricktop, Snatch
Two versions!
That's the proper noun, Nemesis. The god. Obviously this is a different meaning of the word.
Hahaha. Great quote UXM! One of the best lines of the movie
But not all that different since nemesis, the noun meaning arch-enemy, is directly derived from Nemesis, the Greek goddess of vengeance.
McBehrer. You are now my nemesis for doubting my copying wikipedia! VENGENCE WILL BE MINE!
WE GET VENGEANCE EARLY WHATEVER HAPPENS. PROCEED TO THE NEAREST CERTIFIED PARTY SPOT AND DANCE.
I had intended to wait until hitting 150k before putting the additional 40$ in, but now it's time to bust out the wallet again.
I AM SO HAPPY. I LOVE YOU ALL.
"We will post more info on this new Legacy promo if/when we hit the $150k mark"
No one pointed out the 150k is a Legacy promo?
I was waiting impatiently for the 130K mark because I expected something like this from GtG. You rock, guys.
Onward to WWII Legacy !
Huh? They posted the actual card right above that, preceded by: `If we do hit the $150k level, we will send a new hero promo card (ANOTHER PROMO HERO CHARACTER CARD!!!) to everyone that orders Vengeance as part of this Kickstarter. A fantastic promo card! A promo card for freedom! A promo card that looks like this!!!'
So what do you mean?
They mean that they will post the background story of America's Greatest Legacy when the 150k will be reached -as, n fact, this card won't exist unless we reach the goal.
Anyway, I'm excited at the idea that this Legacy may very well lead the fight against the Last Unreavealed Villain of Shattered Timelines.
Oh yeah, where's the bio for that last villain? I'm excited to read his bio.
But I don't care right now, I'm rejoicing over this Vengeance news!
My internet is slow. The picture never came up, it looked as though there was no new card. My bad… internet error. :(
That would be… well… interesting, to say the least.
haha, ok. I just thought I didn't understand what you meant, hence asking for clarification.
Wow! Pledges really spiked now! Email reminder plus awesome announcement having their intended effect, I see 
I already upped my pledge for Vengeance. I cant anymore, due to funding… Let's get more people!