This is indeed hilarious to all of us in the video games industry, as well as movies like Grandma's Boy (Unrated Edition).  It's a great movie and everyone should see it, but hardly representative of what goes on in our industry.

Game Designers on a large project generally fall into two categories: System Designers and Level Designers. Here's a very brief overview of how these roles fit into a game project.

System Designers focus on the nuts and bolts of the individual components of the game like Weapons, Enemy AI, Player Movement, etc.  An example of how they might approach the balance of a weapon is by tweaking the numbers for rate of fire, weapon accuracy, projectile falloff distance and spread of fire.  So, as you can see, they need to be good with numbers and very detail oriented.  The types of specs they create for Programmers and Artists tend to be very detailed with lots of numbers and charts as a starting point for implementation and then they take those numbers and tweak them until things feel right in the game.  That "feel" is another important part of their skill set which usually comes from years of playing games and observing what makes a combination of these mechanics into an enjoyable player experience.

Level Designers are where the rubber meets the road.  They take all of the provided mechanics and bring them all together into the experience that the player sees as they make their way through the game.  Level Designers usually start by planing out the entire experience on paper showing the flow of the level and how the different game components will be used.  They then take this paper map and transform it into a traversable world using whatever 3D Editor that their studio provides (this is a huge simplification of what goes into it, but i'll elaborate more in a later post).  They are, in a way, the director of each individual mission since they rely on pieces from so many others and are ultimately responsible for getting the best experience possible for the player.  Some key components to building a level are placing all enemy units in the world, creating the conditions on which they attack, place ammo in places that the player can easily find, use good layout techniques to ensure the player understands their path and motivations, the list goes on and on.

There are many designers that can fill either or both of these roles, but in my experience most studios are looking to hire one or the other so if you have a skill set that leans into one of these areas it's probably best to focus on that first when you're trying to get started.

In future posts I'll be going into greater detail on these processes and philosophies, but I just wanted to give a brief overview of these two areas to get people a starting point to think about Game Design and also see what specific areas you may want me to elaborate on.  Let me know!

I'll also be posting about books that every Game Designer should own, but for now take a look at what I have listed in my Amazon.com store.