In addition to the fighting game “firsts” we already know about, I realized that Dead or Alive 4 and Under Night In-Birth are two additional “firsts” in fighting games.
Dead or Alive 4 was the first fighting game with an exactly 1:1 playable character sex ratio. When Dead or Alive 4 was first released, exactly 50% of the 16 playable characters (that’s right, I said 16. I’m not counting characters who had to be unlocked) were male, and the other 50% were female.
Under Night In-Birth was the first fighting game with an exactly even playable character sex ratio to not display blatantly obvious fanservice (such as the jiggle physics of Dead or Alive 4). When Under Night In-Birth was first released, ten characters were playable, 5 being male and 5 being female (Hilda was not playable yet).
It would be interesting to hear your thoughts.