I entirely agree with Dopey.
As a former "game" developer I can speak. In game development you have three types of people, coders, meshers (those who makes the meshes) and the colorers (who make the textures and all).
[And in those three categories, you have two subcategories: coders, coders/meshers, meshers, meshers/colorers, colorers].
You start off with the coders who deal with plain-ASCII text all-day and basically see nothing of the game until a later stage.
Here's an UnrealScript example:
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Meshers will work on building in-game objects (characters, maps, cars, etc.) with only wires like this dolphin:
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The colorers will work on the making the colors of the game. Their work will be super positioned over the meshes to make them pretty.
That sounds complicated already right? Well, that's just the start...
As a map designer you have to make sure that you can't "fall off" the map, you have to add trigers and link them to an in-game function.
When you code the game, you'll have different people managing different parts of the game, some that will manage Tcp/Ip connections (networkers), some that will manage user-input and that will try to exterminate hacked controllers. If I start getting too detailly it won't take me 5 minutes to write this reply lol.
I hope this [semi-]long [complicated]post showed you how complicated it is to make a game. Even if IW spent 10 years developing MW2, you would still find a bug. Games are getting more and more sophisticated (new technologies). A few years ago, games would run just fine under one graphic card, then nVidia released SLI (Scalable Link Interface).
With that release, you have to entirely re-write your core to be able to use about 135% of 2 GPUs.
In other words, it is IMPOSSIBLE to release a game with out any bugs/hacks/glitches and not be able to hook anything. As an open bet, I'm willing to bet $10 that you can't write a full game (single player with different maps, multiplayer with split-screen and online play) WITHOUT any things mentioned above.