Croquet for Mac

From Croquet Project:

Combination of open source computer software and network architecture that supports deep collaboration and resource sharing among large numbers of users. Such collaboration is carried out within the context of a large-scale distributed information system. The software and architecture define a framework for delivering a scalable, persistent, and extensible interface to network delivered resources. The integrated 2D and 3D Croquet interface allows for co-creativity, knowledge sharing, and deep social presence among large numbers of people. Within Croquet's 3D wide-area environments, participants enjoy synchronous telepresence with one another.  Moreover, users enjoy secure, shared access to Internet and other network-deliverable information resources, as well as the ability to design complex spaces individually or while working with others.  Every visualization and simulation within Croquet is a collaborative object, as Croquet is fully modifiable at all times.