Tell me if this is a lame idea for a game. You are a creature (I haven't decided what kind yet, but not a dragon) who was thrown out of society and you go back for revenge. Your main quest would be to kill the man who threw you out, but there will be plenty of side quests.
Also, you are not portrayed as evil. In fact, the humans are made to be evil.
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"4000 hungry children
Leave us per hour from starvation
While billions are spent on bombs,
Creating death showers." System of a Down - Boom