It sure does feel like "addictive" is the new "viral": the goal de jour of product strategists. Both are slippery objectives; they are impossible to guarantee and require as much art as science. While optimizing a 'viral loop' requires a ton of trial / analysis / iteration, optimizing for 'addictiveness' requires attention to game theory and user experience perfection.

Here's my theory: an experience becomes addictive when its "thrill-to-effort" ratio approaches infinity.

In designing product (as opposed to drugs or porn), thrill often results from competition, winning, and as a result: rising in social rank.

Not only is it fun to compete for social status, it's a basic human drive. If you give people an opportunity to increase their rank or 'thought leadership' within a community important to them (friends or business colleagues), most people will pursue it.

If web2.0 was all about self expression, this next era will be defined by competition.

But thrill alone does not create addictive experiences. Addiction abhors effort. An experience can't be addictive if it requires too much thinking, input, time investment, etc. And folks, the bar for "too much" is pretty darn low in the consumer product world!

The closer you can get the input to be fully automated (ie, no user effort), the better your chances of creating an addictive experience. Two products come to mind: Nike Plus and Foursquare.

Nike Plus is compelling because it automatically tracks your running workouts via your shoe(how far you ran, your speed, calories burned, etc) and keeps a history of it all for you. No manual data input required (except, uh, the actual running part).

Foursquare is compelling because with just two taps on your iPhone, the app can track all the places you go in the real world and turns "visiting places" into a fun, competitive game. And yes, it would be EVEN BETTER if it automatically recorded your locations without ANY user input, as I often forget to manually "check in" (two iPhone taps are two too many).

In summary, minimize (or eliminate) user effort, add a competitive angle, reward winning with increased social status... and you're on your way to building an addictive experience.

Note: I don't usually discuss product strategy on this blog. But since I spend most of my days talking strategy with clients, occasionally I find important themes that warrant mention. 'Addictive' user experiences is definitely one such theme.