Discrete Skills

The problem, I think with the divide between gamers and non-gamers is the skills required to play. Not Leet skills, or even mad skills, just the basic tool-use that you've likely acquired between the 1980s and now. Gamers might see each individual game as a rehash of something they've learned somewhere else. Even the vague differences in the shape of a controller don't matter much.

I've only got a gamecube and a handful of games on hand at the moment, but let's say you're playing Halo? You run up to a guy, strafe around behind him (making sure you keep him on screen) and melee him to death. To you, this might be a single skill. Two at most. The ability to get close to an enemy and kill them without firing, or dying yourself.

To a non-gamer, trying to do the same thing is several discrete skills. Separate things they have to learn.

The first thing isn't the controller. It's the screen. What do all the little blinking lights mean, which ones are you supposed to shoot. I got my exposure to shooters in Goldeneye. As much as people may argue, shooters have not changed significantly since then.

Once they know what the game is telling them, they have to be able to tell the game to do things. This means using the controller. I started playing games on an old NES system in a basement in the late 90s, and on my cousin's N64 when I would visit them. Holding a controller properly (so you can reach all the buttons) and knowing where the buttons are is more difficult than you might think.

An NES controller had an A and B button, a four ways you could push the D-pad, as well as a start button and select. Jump forward to the Super NES, another two buttons next to A and B, plus two shoulder triggers, start and select. From eight to twelve buttons.

Another jump forward to the N64! Six buttons on the one side (A, B, and 4 C buttons) a 4 direction D-pad, two shoulder triggers, a start button and a Z-button on the underside, as well as an 8 direction analog stick. This puts us at 22 possible "buttons". Adding to this that the basic shape of the controller has changed and we're now working in three dimensions.

Sixth generation consoles!
The Gamecube: two analog sticks (8 directions each) A, B, X and Y buttons, two shoulder triggers, a Z button located above a shoulder trigger, the D-pad and a start button. 28 "buttons".

The XBox: A, B, X and Y buttons, a d-pad, two analog sticks, start/select, two shoulder triggers and a black/white button pairing. The analog sticks "click" to add an extra button. 32 "buttons"

The Playstation! (Dualshock controller) Two analog sticks, four shoulder buttons, a four button set on the left and right sides, start and select. 30 "buttons".

That's between 28 and 30 discrete inputs. We're not even going to get into the fact that an analog sticks can tell the difference between the force being used on them, or combinations of buttons. Now imagine you haven't played a game before and you have to figure out how to use this monstrosity, and you have no idea what you're doing.

So now you've learned the hardware. Time to learn the software!
Just to list the things that people might take for granted that they've learned:
2D platforming
3d platforming
Fine-motor skills
Hand-eye-coordination
Tropes (it's glowing, so shoot it, lots of ammo here: boss battle)
Circle strafing
Basic game puzzles
Basic game cues (red arrows denote where I'm getting shot from, blood on the screen means I'm getting shot)
Use of cover
Grenades
Button combinations

Circle strafing is a tricky one, I think, for new gamers to grasp. I really got started playing video games on a gamecube I got for christmas, it is also my gaming system while I'm away from home, so I'll use it as an example.
In Metroid Prime, you can lock on to an enemy using the left shoulder trigger. While locked on (holding this trigger) you can circle around the enemy by tapping the B button and pushing the control stick in the direction you wish to circle. In some cases, you are expected to fire while circle strafing. For a new gamer, this might be overwhelming.

I intend to take the time to introduce a non-gamer to gaming at some point in the future, so we'll see how the discrete skills approach works.