The story is excellent, definately deeper than the usual games in the FPS genre. I would recommend checking out the book Fall Of Reach too, gives a huge amount of backstory not covered in the games. In fact all the books really do emphasize how huge the scope of the Halo universe is outside of the games. I doubt you have time though to complete all the Halo games and start Reach on launch day but it probably is worth catching up on the story. For the record you could skip ODST as it's not that important in the story arch for Halo 1-3 and Reach.







