The environment is targeted towards visitors to the Computer Museum's Virtual Fishtank exhibit, who I assumed to be fairly naive about computers and to have fairly short attention spans. Instead of having to learn syntactical rules, they become immediately obvious from the affordances and indicators of the interface. The language is strongly typed, with type indicated by the color of the block. The available types are displayed at the top of the screen, and the particular tiles of a given type may be seen by clicking on the type tile.
Tiles become translucent when dragged.