That's the only required episode, but I would watch some of the best ranked episodes of TOS just to get a feel for the characters.
https://m.imdb.com/search/title/?count=250&series=tt0060028&sort=user_rating,desc
(Since Space Seed is ranked fourth, maybe watch the top 4 at a minimum).
Favorite Games: BlazBlue: Central Fiction, Street Fighter III: Third Strike, Bayonetta, Bloodborne
thats a username you habe
- chuckyhacksss