Re: What are you going to play first in Halo Reach?
Uh...one of these:
invasion (i loved it and playing with more armour abilities, best mode ever!)
Campeign (i like fighting AI+storyline sounds cool)
Firrefight (Endless amounts of hunters vs me and my friend= awsomeness)
Forge(probely not actually cause id rather go find out what new things do before i build with them)