Currently on mission 6 playing on normal difficulty. I've enjoyed the last few missions but I'm just here seeking general advice (for campaign; I won't be playing skirmish).
Which UNSC units are garbage? Should I even use marines or just mass tanks and hornets? So far I've just been upgrading warthogs to gaus cannons and using them with tanks and hornets. Once I am near the unit cap I just send my army to its destination and kind of let them do their own thing. I'm sure this wouldn't work on legendary though. Spartans with spartan lasers seem pretty effective.
Have you beat legendary? Legendary co-op might be fun.