At its core, this site is just a collection of activities.
Activities are pluggable modules that, currently, are independent from one another. The base of this site is a platform for running these activities.
Some activities are one-offs—you do the activity and then you're done with it and it can't be run again.
Other activities are repeatable—you can do the activity over and over again as many times as you like.
At the moment, the only thing other than repeatability that determines whether a user can do an activity is the user's adoption level compared with how many other people have already done that activity.
Because I want to roll out lots of activities, some experimental, there will likely be occasional problems that don't surface until a few people have tried the activity. For this reason, I let users set an "adoption level" which states their tolerance to new, un-tested activities. By default, users have an adoption level of "early adopter". This means they will get access to an activity once ten other people have tried the activity. They can change their adoption level to "bleeding edge" to get immediate access to activities as soon as I deploy them. For people that really want to wait until an activity is tried and true, they can set their adoption level to "maintream" and wait until 100 people have tried the activity before it is available to them.
In a follow-up post, I'll dive into the different types of activities that have been implemented so far.
From an unpublished blog post on learning-greek: