Self-expression is an inherent part of almost all video games. By simply being a medium where the audience can interact with the work, they're allowed to make an impact within the game. Even doing nothing at all is technically an expression.
But that viewpoint is pretty pretentious and nebulous. In a practical sense games have two ways most people consider outlets for expression - building environments and player customisation. There are deviations of course, but what you come across in mainstream titles will boil down to one of those two.
To be hyperbolic, building (or destroying) environments doesn't give me much joy. I know there are plenty of people who spend countless hours crafting the perfect urban environment in SimCity or constructing a golden, penis-shaped fortress in Minecraft, but it's not my thing.
What I can burn hours on is thorough character customisation - perfect for my egoistic nature. Most games are very mechanical about this (will you put points into attack, defence or custard pie resistance?), but the real draw is the fashionable side.
It's the perfect way of showing how painfully unique and stylish I am. I have an avid interest in fashion and subculture - though since the general demographic target for mainstream games is not... shall we say 'particularly sartorial', games that let you choose your fashion choices stand out as special.
It's all well and good to have a robust character building system in a game, but if it's all impossible fantasy armour or tattered brown military gear then *snore* - let me wow crowds with sharp suits and bold patterns.

Which, coincidentally, had me all kinds of hyped for New Style Boutique earlier this year. I had much enjoyed the original DS game (to the raised eyebrows of almost all my male peers), and having my fashion tastes not only fully expressed but at the gameplay forefront seemed like a dream.
Funnily enough, it didn't fully meet up to my expectations.
New Style Boutique is a fun and well-produced game, don't get me wrong. But, in order to give something as subjective as fashion tastes win and lose states, the game has a hidden set of rules for what works and what doesn't.
It's surprisingly restricted. For example, I personally hate wearing too many things from the same brand at once (it makes you look like a walking billboard). But because each brand in the game is dedicated to a single 'look', hardcore brand loyalty is the stairway to success.
I had to form an uneasy balance between experimentation and ticking all the invisible boxes the game required. This wasn't punk in the slightest, no matter how much Stage Dive-brand clothing I wore.
Where I found a far better style experience on the 3DS was, surprisingly, Monster Hunter 3 Ultimate. Now, MH3U has more than its fair share of overly-bulky, ridiculous armour sets, but it's sprinkled with some real flair.
Every enemy you fight in the game can be turned into items to wear, and it takes a few kills before you have enough materials to make the full suit. This has the great side-effect of making you work hard for your fashion. When I first started playing, and found I could wear a suit and top hat made from butterfly wings, I was totally blown away.
But the bugs that the suit was made from were delicate, and shattered into dust against my weapon, denying me a carving opportunity. Working out how to reliably get the carves (the trick is to poison them) and gather all the parts took me hours. But the result was pure joy and a fabulous, lustrous sheen.
Even though the different armours are tied to mechanical benefits (each armour set gives a bunch of skill bonuses) crafting an outfit that both looks cool and gives skills you want is a test in lateral thinking.
However,
my customisation ideal is the ability to design clothes myself. It's
not an impossible task (the Sims modding community has been doing it for
years), but the Animal Crossing series makes it breathtakingly easy.The simple, low-poly style of the game means making patterns is a painless process. Spending years of my teenage life doing (mediocre) pixel art as a hobby meant I could go to the Able Sisters tailoring shop and churn out clothing like a Primark sweatshop.
Animal Crossing New Leaf takes the extra step and allows design of clothes of three different styles - as well as making trousers and shoes separate items, so you can create an ensemble from top to toe.
July can't come fast enough. Look out for Nathan Blades Summer 2013 clothing range in an Animal Crossing town near you.

They've
cranked things up for the 3DS – everything is now rendered in 3D, but
the art direction of the originals is still intact, right down to the
goofy freaking out animations when you expose a flaw in testimony.
The Wonderful 101
is partially a technique-heavy hack 'n' slash, partially an action
puzzler. Playing as a superhero with the power of 'unity', you use it
not so much in a 'power of friendship' way, but more of a 'chaining
people together to make giant weapons' kind of way.
Having seen severe delays, you would hope that Rayman Legends would
be brimming with content and gleaming with polish. Well, it's
impossible to judge content from the demo, but the game definitely feels
weighty, retaining all the charm and animation quality of the prequel.
Arguably existing to fill a quota of a Wario Ware game on every Nintendo console, the Wario Ware series have been great for demonstrating how to use the hardware's quirks for interesting ideas.
The first public showing of the game in Europe, Animal Crossing New Leaf's release date crawls closer and closer.
A spiritual sequel to the Japanese-only Namco X Capcom, Project X Zone (pronounced
"Cross Zone") takes iconic characters from the franchise histories of
Sega, Namco, and Capcom and has them fight to save the say in a very
flashy turn-based strategy game.
One of the handful of games demonstrated at the Nintendo booth that are ports of an existing titles (Resident Evil Revelations and The Cave were also available), I bring it up Deus Ex for the unique way it uses the GamePad.