Not for nothing did it have «terror missions», which lived up to their name as the initial weak little - grey - men Sectoids got politely pushed out of the way for the
likes of the Chryssalids,
hideous Giger style
monsters who didn't just kill your jumpsuit - wearing soldiers, but implanted them with
hideous alien wing - wang to turn them first into a zombie, and then into another bloody Chryssalid.