Not usually, if the game has been out for awhile, there probably will be an update that you will have to install so you can play with others on-line. But, this is only to match the version that other players are using. I've known of only 1 game that has required you to install a patch/update, and that was Neverwinter Nights: Diamond. Other than that, you can play the game by yourself without updating, ever!
Yeah, but usually it's a good idea to update since they may have fixed a certain annoying bug that you get or just optimized the code so that it runs better on your computer.