1. DDO is based on Dungeons&Dragons core rules.
  2. Awesome graphics.
  3. Elite difficulty.
  4. Almost infinite Heroes builds.
  5. A wide diversity of Quests, Monsters, Maps, Items, etc.
  6. Use of movement in tactical combat, and the way Melee & Ranged combat is implemented.
  7. DDO's nursing to balance issues.
  8. The social feature of Partying.
  9. Dungeon Alert.
  10. DDO Forums.