Character, Morality and Reputation

Detailed player profiles with many stats, far beyond a single level number.
A perception / charisma-style reputation.
Players may choose to be evil, but then they're largely confined to an underworld with other bad actors, and may be refused entry to towns, villages and cities by gate guards.
Evil players can redeem themselves, but it gets exponentially harder the further they fall.
A truly good person can be liked by both sides.
Morality is judged by how the player handles quests, main and especially side quests.
(Idea) Track personal morality separately from standing with each side.