In the Civilization Series, Albert Einstein works as a unique scientist or famous person that appears in one of the player's cities. The player can then choose to have him inhabit the city or consume him for bonuses, which depend on which Civilization game is being played. He may also be used for other game purposes, but that varies from each iteration in Civilization
Red Alert Series
The alternate universe of C&C Red Alert can be directly attributed to the actions of Albert Einstein and his use of the Chronosphere to alter history by erasing Adolf Hitler from the timeline. As a result the Soviet Union becomes the biggest threat facing the Allies in this new tangent timeline. Einstein's technology allowed for other high tech advances in Allied technology such as Chrono Tanks, Prism Towers, Chrono Troopers, and Prism Tanks. These act as direct counters to the Tesla technology employed by the Soviets.