Well, in answer to {Ron!n}'s original question: difficulty of coding doesn't have anything to do with gameplay length or content.
The coding that is done in a game is for models (the people and objects on the screen) and the engine (which controls movement and animation).
Once the engine is complete, the programmers then write a "script" which indicates the story line. If you've used the Warcraft or Crysis map editors - it's very similar to those. The engine and script are 100% separate, a 1-hour game takes the same amount of code as a 100-hour game, provided you're using the same engine.