Mass Effect 1: World Without End

Every 50,000 years, an ancient machine race invades, trapping the galaxy in an endless cycle of extinction. These machines wipe out all advanced organic civilization with ruthless efficiency, destroying all evidence of their existence, leaving behind only scattered ruins of technology.
Commander Hayden J. Shepard of the SSV Normandy recruits an elite recon squad to cross a turmoiled galaxy in a desperate race to stop the return of an enemy who holds no mercy. To prevent this outcome, Shepard must act outside the limits of the law without remorse and hesitation. Her only imperative is to preserve the safety of civilized life in the galaxy - at any cost.