1. Koopalings - The Game. First time the Koopalings are playable in a main-series game. Also doubles as the second game in which Mario is an Antagonist (after Donkey Kong Jr, which was such a while ago) and the first game in the entire series to have a member of the Koopa Troop as the sole protagonist(s), the Koopaling's first appearances in 3D Mario, and first time Peach, Yoshi, Toads, and as a whole the entire Mushroom Kingdom is an antagonist, as well as the first traditional Mario game with a Kirby's Return to Dream Land / Triple Deluxe / Planet Robobot / Forgotten Land-style plot twist that may change your view of the Mushroom Kingdom forever. Also juicy in Lore, providing (indirect) background information on the series and how the mushroom world is now.