I've played through the single-player campaign and the damn thing is short. Microsoft expects over 3 million people to participate in the upcoming Halo: Reach beta. And yes in order to gain access you have to buy a Halo 3: ODST. Now, it's not a bad game, but it amazes me how many people actually bought it - during the first two weeks, ODST sold over 2.5 mill. Let's be fair, it's single-player campaign is very short and it carried a full retail price.

Anyway, after so many years Halo is still one of Microsoft's top 360-exclusive franchises and, by the look of things, it will continue to be as successful in future.