Team Fortress 2: Mann vs. Machine

In the former, Redmond and Blutarch Mann come to a truce, only to discover about their long-lost brother, Gray Mann, who kills them shortly after. In the latter, Saxton informs RED and BLU that they're out of a job, and re-hires them as a united force to combat Gray's robot army. Those mercenaries attempts to prevent the horde of AI-controlled robots from escorting a bomb to a drop-point located in a Mann Co. facility.