An anonymous reader writes: Game design is one of those jobs everybody thinks they can do. After all, they've played a few games, and they know what they liked and disliked, right? How hard could it be? Well, professional game designer Liz England has summed up the difficulty of the job and the breadth of knowledge needed to do it in what she calls 'the door problem.' Quoting: 'Premise: You are making a game. Are there doors in your game? Can the player open them? Can the player open every door in the game? What tells a player a door is locked and will open, as opposed to a door that they will never open? What happens if there are two players? Does it only lock after both players pass through the door? What if the level is REALLY BIG and can’t all exist at the same time?' This is just a few of the questions that need answering. She then goes through how other employees in the company respond to the issue, often complicating it. 'Network Programmer: “Do all the players need to see the door open at the same time?” Release Engineer: “You need to get your doors in by 3pm if you want them on the disk.” Producer: “Do we need to give everyone those doors or can we save them for a pre-order bonus?”'