For my final (aka "thesis") project at ITP, I re-created an earlier project, Written World, which came out of a group project for Clay Shirky's Designing Conversational Spaces class, which in turn was based on Andrew Badr's awesome project Your World Of Text.
Written World was a communal realtime free-form text world, overlaid on a street map of the user's physical location. It incorporated elements of online chat, ASCII art, and graffiti to explore and create a bridge between the physical and virtual.
Mostly, Written World was an experiment to see what people would do when presented with their location on a map as the primary context, and no prompt or topic to guide them, other than what previous visitors had written around that location. (And, of course, a glowing cursor that could be moved around by typing, the arrow keys, or clicking.)
While visitors were able to write whatever they wanted, the world was built with mechanics to encourage constructive participation. For instance, to help incentivize the removal of spam and other inappropriate text, I created a cool animation for the deletion of text. People seemed to really like this, and it appeared to work well, the few cases I saw of hate-speech were always removed by another user within a few hours.
Less successful was the system for "echoing" text. The idea was to add permanence to content that users thought was good, basically analogous to upvoting. I had hoped people would discover this mechanic on their own, but pretty much no one did.
Unfortunately, due to the costs of serving a realtime chat world, I shut down Written World after a year. This was largely due to my own inexperience at building software at this scale, as it was inefficiently consuming a good deal of server resources and so was expensive to run.
Below is a video of me demonstrating it during a presentation at ITP while it was live.