Originally Posted by
warty goblin
I find it notable that ME 1 and Halo 1 both mostly sidestep the worst excesses of "commander, get the Cypher to the Conduit before Lord Vile activates the Converter, or else the Archon will destroy the Nexus!" sort of story. I suspect that this is because they're the first games, which allows them to use information as an objective much more readily than later titles - figuring the Reapers out is satisfying, but you can only play that card once. Also they're just free to introduce stuff in a way that later titles aren't by dint of being first titles. The Flood are a great end of the second act twist, but you can't really introduce secret space zombies multiple times.