Well, to have the slightest hope in hell, you've got to have more than an idea.
Heres the thing. Groups like Valve, Electronic Arts, Blizzard, NC Soft, and the many other game developers out there have people who do this for them for a living.
The decisions on a game are made in committee, rarely does a game go from idea to game even mostly unchanged.
But the things that have to be presented...
You have to have a story, and an appearance. Generally they are going to at least want to see some character and setting concept art. They want to see an artists conception that lets them know what the game is going to look and feel like right from the start.
Now, depending on the type of game here, theres alot of other stuff.
For instance, if you were proposing a fighting game, you would need detailed notes on game mechanics. Besides its look, the reason people give a fighting game attention is if its fun to play. You would have to have a concept that fit the x box control scheme and provided complex and engaging gameplay.
If you were proposing a first person shooter, on the other hand, the two most important things would be story and level design. One first person shooter can be like another in functional mechanics but be completely different experience because of the level design and the obstacles that must be overcome.
You would also probably have to have an idea about enemy AI, which means knowing about programming.
Each type of game presents its own problems.
In all honesty, if you really want to get any game ideas out there, you need to be able to program them. This would allow you to work on games, learn all about how they actually work when you get down to line code and graphics models. At that point, you could work on a game and actually begin making it yourself, and then when its complete enough to show an initial concept to a producer you could go in basically requesting funding to help complete a project. No guarantee, but if you deliver them a grand slam it would pay them to produce then you can get the additional expertise that can put polish on your idea and turn it into something people scramble to find a copy of christmas eve. [ WittyUsernameHere's advice column | Ask WittyUsernameHere A Question ]
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