Basically a board of people come together and brainstorm all ideas that will be incorporated into the game. They then do practise sketches of the surroundings which are made into 3D designs on the computer. They then set boundaries on the game play field so you can't walk through of get stuck in walls etc. After the scene is done they create the characters. they get practice sketckes of the characters then get a person to act out the way the characters will move on camera. the graphics designer will then get the 3D model of the character and look at the movement that the game producers want. They then move the compuer simulation character model in conjunction with the specified movements making the character move as it should. The movie scenes are made and the character(s) is then incorporated into the gameing field and a few games are produced. these games then go out for testing(What a great job, lol)the game testers will check all of the boundaries and make sure the game runs correctly. After the testing is complete the games are produced in quantity and shiped out to you :)
from what i understand, they create the games, (sometimes taking up to three years,) and they pay people to test them out, to see if what they wanted to accomplish with it was. (sometimes they put certain restrictions on the game, so that you can't just do whatever, it has to be specifically guided. like not being able to go into cracks, or to be able to stop at cliff edges in some games.) they try to make as many possibilities as possible, but they also don't put too much time into it. (sometimes they have glitches, like being able to get five or six or seven or more bottles on occorina of time, the zelda game, or being able to get more hearts) but if you can't do it on the game, they didn't program it into it,or out of it.Video games or movies
Video games, are written by script, that tells the gae how to run.