The traditional approach to designing a game with a narrative has been for the game designer to work like a movie screen writer: he creates a series of “scripted” events at various points in a game level which are followed from beginning to end, and which always occur in the same order whenever the game is played. For example, the designer might decide that when you go around a certain corner, an alien should jump out at you and start attacking. Half Life was one of the early games to do a really excellent job with this sort of approach, and provided some of the most memorable moments in gaming up to its time.

By contrast, some newer games have embraced a more open, flexible approach to the game experience, which is generally known as “Emergent Game Play”. Rather than specifically writing in dramatic encounters, designers will create various game elements that interact in complex, consistent, and interesting ways. So, instead of having an alien always jump at you as you go around a particular corner, that alien would instead be roaming the halls on a search pattern, perhaps stopping to look for food once in a while, and generally actually doing something even when the player isn’t watching it, rather than just waiting to jump out at the player. Or, instead of dispatching said alien with the gun the game designer provided, the player might instead shoot a cylinder with poisonous gas contained therein and then beat a hasty retreat, closing and locking a door behind him until the alien expires.

The advantage to this approach is that every player gets a potentially unique experience, and that the environments feel much more real. The disadvantage is that creating this sort of sandbox is significantly more work and takes considerably more testing. (There’s an interesting article at Gamecritic that uses the recent games Call of Duty 4 and Crysis to contrast these two approaches to game design.)

Another interesting development in recent years has been the inclusion of Map Editors with games. These allow players to create their own levels and to distribute them over the Internet. Dubbed “user-generated content”, these additional battlefields extend the shelf life of a game considerably without much additional investment on the game company’s part.

One of the most interesting experiments in user-generated contents is the world of Second Life, which provides its users tools, a great big open space, and not much else. All the content in its game world is created by users.

But all of this gets even more interesting when all these elements come together in something I’m calling Emergent Game Design, where the game players take the tools that the designers have provided them and create something completely different out of it — effectively turning one kind of game into something completely different.

One of the first examples of this I saw was Tower Defense in Warcraft 3. Normally, Warcraft 3 is a Real-Time Strategy game, in which one commands fantasy armies around a battlefield from an overhead view. The key gameplay elements are gathering resources, building a base, amassing an army, and wiping your opponents from the map.

Though it was built with Warcraft 3 and its editor, Tower Defense provided a completely different experience: the player is presented with a path down which gigantic armies of enemies march. The player doesn’t have any mobile offensive units, but only the ability to build defensive towers along the enemies’ path. There’s no resource gathering, no army building, just a very focused effort to keep the enemy units from making it all the way across the screen. (A nice version of the TD concept that you can play in your browser is Desktop Tower Defense, which I recommend you avoid if you have any pressing engagements in the next two hours.)

I saw another interesting example recently while playing Team Fortress 2, a multiplayer class-based shooter where you can adopt the role of a soldier, a combat engineer, a sniper, or a medic and join in 48 player battles across the Internet. It’s a really well-done game, and a lot of fun if you enjoy simulated combat.

However, some enterprising gamer took the level editing tools that Valve provided with the game and created a map called Skyscraper. Skyscraper completely revamps the game, segregating the two teams into discrete areas which allow no direct interaction whatever. The challenge suddenly changes from besting your opponents in combat to getting to the top of an enormously tall and perilous vertical space in the shortest possible time. Team members no longer help each other destroy the opposing force, but use their weapons and combat tools to help each other get progressively more altitude.

Another example: English educators used Neverwinter Nights, a superb fantasy role playing game with good editing tools,  to further educational goals by rebuilding the game to require literacy and numeracy skills, such as comprehending written material and calculating area to load a ship’s hold.

The fascinating thing about these examples is that players have been given rich enough tools to not only choose their own approach to achieving the game’s goals, but to actually carve out their own game with entirely different ends. Though Tower Defense, Skyscraper and the West Nottingshire project were all created with an existing game’s tools, they are utterly different games from those that provide the technology they’re built on.

Which brings us back again to Second Life. Since it has an exceptionally powerful set of editing tools and everything in its world is created by users, it seems logical that it would be a rich field for Emergent Game Design. And that turns out to be true. Second Life members have created in-game versions of lots of gaming standards, such as slot machines, trivia games, etc., but have taken things much further.

There are many examples of original games that have been created in that world, from first person shooters to role playing games to entirely original creations. In fact, a game created in Second Life called Tringo has been such a success that various companies have licensed the game design to create Game Boy and standalone PC versions of the game. And, in spite of persistent technical and business issues, Second Life continues to amass a larger and larger following because of this strength.

So, what can we take away from this? Lessons for the game-player:

• Try some of the top-rated user generated maps for your favorite games. You’ll almost certainly have a good time, and you might discover a few gems.
• If you have ideas you’d like to try, don’t be afraid to crack open the editing tools that come with your favorite games. Many have active and helpful communities that make it pretty easy to get started.
• If you’re interested in getting into the game industry, creating a successful level or mod for a game is one of the best ways to do so.

For game designers:

• Emergent gameplay and rich worlds are worth the extra effort. (Full disclosure: I used to work for Origin, whose motto “We Create Worlds” shows a certain bias to creating complex game spaces.)
• Your customers are smart and collectively have way more free time than you do. Give them opportunities to use those facts to your advantage.
• If you want your game to have a long life, one of the best things you can do is provide the community with great tools to tweak the game. Even if only 1% of the game owners ever launch an editor, and only 10% use user-generated content, it will keep interest alive far longer than would have otherwise been the case. And if you can lower the barrier of entry by building easy-to-use editors and content browsers into the game itself, you might just hit a gold mine.