Upon loading the app, players will be confronted by a giant black cube. When they approach the cube, they find they can tap it and start breaking into it.
The cube is formed of thousands upon thousands of smaller cubes, apparently, and the twist is that it's not just you tapping your way into it - it's every other person using the Curiosity app.
A few shots of it flashed up on screen behind Molyneux and presenter Geoff Keighley and it really does look like a giant black cube suspended in white space.
http://www.eurogamer.net/articles/2012-06-04-peter-molyneux-unveils-experimental-curiosity-app
Every player is tapping on the same cube but only one person finds the secret.