- last post: 01.01.0001 12:00 AM PDT
3 Reasons:
1. It uses the same engine (graphics, AI, etc.)
2. It's an expansion to the Halo 3 game
3. Halo 2: ODST or Halo 2.5 wouldn't make sense, we'd be going back in time. If anything, it has to have Halo 3 in the title to signify that it's after the Halo 1, 2 and 3 games.