The protagonist is somehow unusual compared to rest of her kind, either she has a skill no other has or is significantly more talented than the rest, or perhaps she's just "different" in some unexplainable way.
Alternate name: Extraordinary protagonist
The first video game about Unusual protagonist was released on December 16, 1990.
This may be apparent immediately, revealed as part of the introduction, or much later into the game. If the latter is true, then this is a spoiler tag.
Use unique protagonist instead if he/she/it is that unusual.