Before embarking on a mythology role-playing game, students need a working knowledge of Greco-Roman mythology. As a minimum, students should be acquainted with the main pantheon of gods and domains. Beyond that, these myths are a good starting point.
The Odyssey: Students need not know much about this book. I tread lightly here because students read the entire book in ninth grade English. It helps if they understand the following:
The Trojan War:
The Aeneid : It is not necessary that your students know they entire story. Since the RPG is loosely based upon the journey of Aeneas, they should have familiarity with the following ideas.
Students need not be experts. Due to the popularity of the Percy Jackson books, they will probably already have familiarity with of these many monsters and scenarios. However, the more comfortable students are with the mythological world, the more vivid the RPG will be for them. They need to know that strangers should be treated as guests, gods should be respected and never challenged, and most importantly, fate is fickle and fairness cannot be expected.
How you acquaint your students with the myths is up to you. Over the years, I have done a number of different projects to teach mythology, but by far, the best vehicle I have found for teaching these stories is simply to tell them orally. I tell one myth every Friday and the class loves it and more importantly, remembers it.