Stratis is a d20 tabletop role-playing game set in an alternate reality, with a unique Mastery and Training mechanic. This publication contains all the essential rules and information necessary for gameplay. The system provides extensive customization options with minimal effort required from players, along with a diverse array of monsters and challenges that a Guide can integrate into the narrative. While it is feasible to play using only pencil and paper, we recommend the use of a battle mat, dice, and representations for creatures and characters, such as miniatures, to enhance the overall experience. This system is well-suited for both experienced players and newcomers, and all participants are welcome.