Destructible environment and the off-screen action in terror missions. You'd never be able to save them all (attacked civilians), but where your team did stumbl

Destructible environment and the off-screen action in terror missions. You'd never be able to save them all (attacked civilians), but where your team did stumble into an instance of the aliens grinding through a bunch of still-alive civilians they made a difference far more palpable than any sequence of artfully scripted set-pieces could ever achieve.