I feel compelled to follow the trend of making "of the Decade" lists. So here are the trends in games over the decade. I had a hard time determining my own criteria for what I considered to be an important trend.

I decided on the following: an important trend is a recurring adherence to and iteration on a mechanic, setting, and/or execution of design over the course of the decade in games which appeal to the critical body (reviewers and pure critics) and myself or gamers I consider to share similar gaming interests.

I'm also going to limit myself to a two paragraph maximum per trend (other than the first one) because, if I did not, the discussion of each trend would span several disparate walls of text. These are in no particular order.

Social Play

No particular order, but it seems almost negligent to suggest that any trend in this list trumps the emergence and popularity of social gaming. And I'm not referring to anything that Zynga or Playfish are doing with Facebook games right now because their long-term relevance seems somewhat dubious. It would be absurd to not mention their existence given their popularity the time of writing. No, social gaming is embodied in games like LittleBigPlanet, Rock Band: Beatles, Halo, Call of Duty: Modern Warfare, World of Warcraft, and so many others.

So essential is social play to the modern gamer that there have been a slew of games such as Left 4 Dead and Army of Two which put a focus on playing with a partner or friends (at the expense of the solo experience). And, more than any other major technological or game design advent of the decade, no one deserves more credit for this trend than Microsoft for Xbox Live. They're not the first to have the idea of a major social gaming platform, but their execution, especially at the time, was unmatched.

It's fascinating to watch the evolution of long-running series as they adapt to the changing gaming climate (and the cultural/economical relevance of Generation Y). Started in 1996, Resident Evil has had seven major entries into long-running franchise over the years. When the series trademark gameplay started wearing a bit thin around the days of Code Veronica (2000) and Zero (2002), Capcom retaliated with the critical and commercial hit Resident Evil 4 (2005). Capcom's next major release, however, despite there being no need to deviate from the core design of Resident Evil 4, was the cooperative-focused Resident Evil 5.

Given the absolute cultural domination of broadband internet and services like Facebook and Twitter, which promote an enthusiastic mindset of the sharing of daily minutiae, the elevation of games as an active, social bonding experience between people is hardly a surprise. World of Warcraft is the logical next step from playing Dungeons and Dragons or simply growing up on games like Final Fantasy. Why play alone when your best friend is also on Xbox Live playing the same game?

Enjoyable Realism

For a form of entertainment whose consumers commonly cite the benefit of the medium being a supreme "escape from reality," the biggest games of the decade are fundamentally grounded in reality. The Sims, one of gaming's biggest mainstream phenomenons, is a game where players manage the day-to-day operations and routines of humans called Sims. Games like Gran Turismo and Forza Motorsport popularized the simulation racer with absolute commercial and critical success.

Call of Duty: Modern Warfare took its trademark gameplay to the modern day and put players into implausible but topical scenarios in our shared concept of the world we live in. Grand Theft Auto 4 brought gave us a New York City sandbox to drive, kill, and steal in. Sure, they're power fantasies, but they're incredibly successful power fantasies that don't reach to the depths of science fiction or high fantasy for their subject matter.

This is the one trend that I don't have a thorough understanding of and any explanation I make is reaching into unfamiliar sociological depths. If I had to guess, I'd say the Internet and modern communication has had such a profound impact on the modern gamer and game developers to the point where real life is ceaselessly interesting. The days of sole pen pals from other countries are gone; every day, any day, anyone with an Internet connection can look up factual information on other countries and cultures and talk to people from them. Why go to space when games like Far Cry 2 can portray the beautiful, harrowing reality of Africa? That's not to undercut the role of fantasy and science fiction, as the success of Halo and Harry Potter are huge, but the tight-knit integration of these titles with our own concepts of reality still holds true.

Emergent Story-Telling

Something that most of Nintendo's games and every sports game in history realized ages ago is that the story the player tells is always more enjoyable and interesting than the one that a designer or writer tells. This is something that Maxis realized and embraced with The Sims (and even moreso in its two sequels). Designing zany behaviors and allowing (and encouraging) players to experiment with zany situations for their Sims will yield the most amazing play experiences. And looking at some of the major successes in gaming over the last decade which are actually major AAA games in genres that typically rely heavily on static storylines, it looks like designers are starting to try and adopt an emergent narrative design.

Games like such as Left 4 Dead, Far Cry 2, and Portal all provide story layered on top of player-driven gameplay experiences. Left 4 Dead focuses on the interplay of very defined, well-written characters in a semi-random gameplay environment to flesh out the story of its game world as players engage with the game systems. Far Cry 2 provides a narrative impetus and little else as it lets its players loose into its world to achieve a given goal while the gameplay systems provide for a consistently dynamic and unpredictable experience.

And Portal, while not actually having any emergent story-telling mechanics, has an entertaining antagonist provide the atmosphere for gameplay in a short game progression which ends up feeling far more free and dynamic than it actually is. None of these games are overly heavy-handed in the way they tell their story: once they give the player control of a character, they let the player define the experience. This is one strategy that Nintendo seems to have known all along.

Musical Play

We late-teens and twenty-somethings like music. A lot of us like video games too. Almost no one realized this quite like the partnership of Red Octane and Harmonix when they released Guitar Hero in 2005. Harmonix aced the utilization of plastic instruments as a medium into the cultural collective's dream of being a rock star like no one before. It was popular and it worked well. When Neversoft took over the reigns with the forgettable Guitar Hero 3, though, Harmonix took their thought train to the next level: we like music and music is a shared experience. Harmonix realized that video games, like nothing else in the world -- not even alcohol -- has the power to bring four adult males together into a single room to pound on plastic instruments and sing "Don't Step Believin'" at the top of their lungs. Alcohol is still nice, though.

I said almost earlier because, to me, no one realized the sublime combination of music and video games like Tetsuya Mizuguchi and the crew at Q Entertainment with 2001-2002's Rez. A game which took some traditional ideas of what games were (reflex-dependent and progressive) and put that experience inside a digital soundscape unlike any other. The game provided a static musical track as a base line and every gameplay interaction layered ever-fitting audio cues on top of that to create what is still, in my mind, the ultimate music game.

Reward

Nothing keeps a game sticky like the Skinnerian model of reward smoothly integrated into game design. Let's just set aside our thoughts about ethics for a moment.

I mentioned earlier that Microsoft was ahead of the game, so to speak, with the design of Xbox Live for the Xbox 360. One such way was the addition of persistent per-game achievements for every user. The advent of Xbox Live achievements introduced operant conditioning into the mainstream gamer's expectation set for current generation games.

And, as to be expected from such a form of reward, achievements took on a life of their own with every platform catering to seeming to cater to the commonly understood "core" gamer (Xbox 360, Playstation 3, Steam) adopting some form of the mechanic. "Achievement whoring" is a commonly used and understood term in the lexicon of a current generation gamer and is likely to continue being so in the future. Even World of Warcraft, already the video gaming analog to a slot machine (putting aside virtual slot machines for sake of the comparison), added achievements to its arguably ethical list of ways to keep people playing.