Super Mario Bros orginal trilogy
The Donkey Kong Country original trilogy
The Soul Blazer Trilogy (including Illusion of Time and Terranigma)
The original Legend of Zelda trilogy
Sonic the Hedgehog original trilogy
The Phoenix Wright Ace Attorney trilogy
The original Murayama Suikoden trilogy (1-3)
Not really an official trilogy: but the Kitase Directed Final Fantasy trilogy: Final Fantasy 6, 7, and 8
The Ogre Battle trilogy (Ogre Battle, Tactics Ogre, Ogre Battle: Person of Lordly Caliber)
The Witcher trilogy (but will have a fourth game soon)
The Victoria (Paradox) trilogy
The Crusader Kings trilogy
The Final Fantasy Saga/Legend trilogy
The Romancing Saga trilogy
The Mana/Seiken Densetsu trilogy (Mystic Quest, Secret of Mana, Children of Mana)
I describe myself as a little dose of toxic masculinity.
