Supply and Demand; Chronological (Score 2, Insightful)

The idea that stuff that should be unavailable to children is automatically more mature, has been spectacularly antiproductive.
Example of logic: "Wow, Bobby got drunk and slept with the teacher, and he's only a sixth grader! Awesome! I'm gonna ask him how he does it!"
Labeling things "M" adds about 25% interest among young teenagers, because we advertise sex and drugs as too fun to be legal. People reach for things they think will be useful in making them happy. For inexperienced people looking for fun, illegal looks like a pretty good start. If you're looking to make a game for an adult you're taking a lot of assumptions for what you think they will be reaching for. Any masterpiece you create to charm an adult audience will be virtually unadvertisable, and likely will be a commercial failure. Anybody looking should buy Okami. They would be in the first 500 people to do so, for effect, drink a Tab soda with it.

Child Gamer

14 fully automatic weapons that can be carried at once and ready to fire in any order within a second of each other.
Immense piles of (crappy) enemy armor, clothes, weapons, potions, and lunch monies
Dead Hookers that pay you
Complete physical dominance over a physical world
Self respect with occasional awe
Control over an economy.
Really funny stuff.
Charming stuff that makes you a little happier.
A compliment that actually pleases you

Video Games End Here
Office Software Starts Here

Spousal apologies
More free time/money
Inner Peace/Contentment

Dead Gamer