Persona as a setting has a number of themes and concepts that are inherent to it. This file will explain what is and is not thematic for Persona.
Thematically, Persona takes several cues from Jungian psychology, exploring such concepts as the transformation of the self, the idea that people are seen in many different ways by the people they interact with and thus possess many selves, and the idea that the self is also one's own worst enemy. There is a strong focus on personal growth and self-understanding, and on how free will influences what direction that growth and understanding take.
Persona also has a strong focus on ordinary life in the face of supernatural occurrences, and upon relationships. Characters may have families and friends, they may go to school or work, and they may blow off steam afterwards and generally enjoy their daily lives (or not) as any one human being might. Regular life and relationships may provide a source of stability when dramatic events take place in the characters' lives; or, when they go poorly, they may operate to test or even break a character. Relationships, in whatever form they take, are very important in Persona. A character needs to encounter others to develop.
Thus, Persona is a setting where the exploration and growth of one's self takes precedence over exploration and growth of the world. In this sense, the rest of the world is merely a stage, providing events and settings that influence what a particular player character has and will yet become.
There are accordingly a number of themes and ideas that are not supported by Persona MUSH:
Persona is not a setting where the focus is on 'working to change the world'; instead, the focus is on 'changing the individual,' and on how people react to great events. This theme is not well equipped for characters who can only be fulfilled by effecting dramatic change in the world; the theme is much more about the journey than about the destination.
'Good' and 'evil' as concepts are much more abstracted in Persona. The game is not suited to the classic templates of 'cackling villains twirling their mustaches while plotting to take over the world,' or 'pure-hearted heroes striving to save the world.' This theme examines the condition of 'humanity' rather than the conditions of 'good and evil': every character in Persona is capable of the purest and most foul of intentions and acts alike.
While player and non-player characters alike can die in Persona, mass death and violence is the strong exception rather than the norm. The scope of destruction rarely reaches the level of city blocks, much less entire cities. Significant criminal activity in Persona's setting will be treated much as it would in the real world.
Terrible and tragic things may happen to characters in Persona, but this is not a theme that emphasizes only the cruelty of the universe. Even in the darkest moments, after all, there is a light of hope. Comedic and cheerful things are just as likely to happen as something dire. The interplay of both is important in Persona.
Lastly, Persona-- despite having some advanced science in its theme-- is not a science/technology-focused game. The vast majority of technology in Persona is roughly on par with that readily available to the average person in the modern world, and the potential of science does not stretch beyond the bounds of what might already be possible in the real world. High-powered, supernatural-affecting, or unusual technology is rare in this setting, and in the hands of very few people.