The San Andreas is strike-slip fault, in which opposing blocks of rocks slide past each other horizontally. A big San Andreas quake can spark fires and other mayhem, but it can't displace water and flood San Francisco. Hough said the movie got one aspect right: The tide suddenly ebbing out signals a tsunami is coming.
Games like Overwatch, Fortnite, Call of Duty, and so on require online servers to play generally, although in the case of Call of Duty, you may be able to play its offline singleplayer campaign mode even without online services active.