It is truly what we make it. The first leg of the game will be to level and beat bosses. The second leg of the game will be to survive it, whether that be through connections with other players or sheer will power. The third leg of the game will be a return to reality and to the game itself. There will be a lot of aspects from SAO thrown in.
When you create a character and class, I want you to think, how will this work out in the long run? How far will this character get me. Every character has the potential to be epic, however some will succeed better than others. In video games, there is a ceiling that some characters just can't break through. A healer will never make it as the last person standing. A tank will never be able to survive a boss battle alone, also. When you are making your character, I want the thought to be "How will this character ensure that no one dies?" That doesn't mean only the character's in game abilities. The personality, the characteristics, the development. These creations will not be static. Unlike MMOs such as World of Warcraft, where the character does not develop except for its skills, Mythius will allow for character growth both emotionally and physically.
As for a specific categorization of what type of RP this will be, I am purposely avoiding answering that because there is no one answer. Consider Mythius to be your life, not just one aspect of it.