it is amazing how in halo you are in a constantly interacting world. like every time you return to a place that you had not been to for a while, it appears that a battle has occured, or there has been a shift in the ground forces. it just goes to show how much work they put into the game. i didnt even fully realize that it changed so much until i started paying attention to this stuff later.

Because your mom fell on them! HAHAHAHA!!!!

Well, its kind of hard to explain, but is actually quite simple, it is tricky to fit all of them in, but here it goes. You know the building with the map room it it, where at the early parts of the stages cortana says "Hurry, dont let them lock the door", well in the big room that is attached to the outside, go down the first ramp, and on that platfor there, drop off all of your marines there before go down to get the maproom (after you unliocked the door) and when you come back up, they are all alive (and yes, unfrozen) but make sure that there feet (or tires) if in warthog on are on the ground, or they will die, its kind of tricky because its hard not to run them over, or dropping them off and driving away without some marines climbing back in. but if you can do it, you can save them!

how do you save em?

Remeber when your close to the maproom, foehammer radio's in warning the marines that they have covenant drop ships in bound? well thats what happened, the covenant got them, I also know how to save every single one of the marines (except the ones already dead on the rocks and stuff by the flipped warthogs.

Maybe the invisible Elites got to 'em?

its part of the plot. plus, have you ever noticed the blood goes away after ytou beat the crap out of a jackel corpse? same thing. lag prevention.