If we were to create a new operating system and user interface knowing what we know today, how far could we go?" Further, what kinds of decisions would we make that we might have been unable to even consider 20 or 30 years ago, when the current operating systems were first created?

"Existing operating systems are like the castles that were owned by their respective Lords in the Middle Ages. They were the centers of power, a way to control the population and threaten the competition. Sometimes, a particular Lord would become overpowering, and he would declare himself as King. This was great for the King. And not too bad for the rest of the nobles, but in the end -- technology progressed and people started blowing holes in the sides of the castles. The castles were eventually abandoned" -David A. Smith

The Croquet project is an effort to develop a new open source computer operating system built from the ground up to enable deep collaboration between teams of users. To do this, the project seeks to define and develop a system is focused on the simulation and communication of complex ideas. We call this "communication enhancement" - the direct extension of the abilities of humans to develop, understand, and describe even the most complex simulations.

Croquet enables this communication by acting as the equivalent of a broadband conferencing system built on top of a 3D user interface and a peer-to-peer network architecture.

Croquet is designed to be an operating system for the post-browser Internet.

Croquet is a computer software architecture built from the ground up with a focus on deep collaboration between large numbers of users.

Croquet makes it possible to change and author virtual worlds in collaboration with others inside them while they are operating.

Croquet is a fully dynamic software environment where everything is a object manipulable by all participants.

Croquet is multi-platform and fully interoperable across different computer systems. Croquet utilizes a highly portable virtual machine that runs bit-identical on Windows, Macintosh, Linux, and ultimately on its own hardware…yielding complete interoperability.

Croquet utilizes a software environment where anything can be created or represented; where everything can be modified; where development and user environments are one in the same.

The emergence of software monopolies removed any encouragement to innovate on the platform.

Compare a modern PC of 2004 to the first Macintosh shipping in 1984 and the major difference you will see is color. The fact that these dominant systems were created in early bound languages made it impossible to easily modify the foundations of the system either by the developers or by third parties.

Rather than attempting to adapt the business and commerce-centric web page metaphor for teaching, learning, and collaboration, Croquet is a new media designed from the ground up for social and collaborative spaces. This is not to say that existing web pages have no part in Croquet. Because Croquet can display web pages as part of Croquet scenes, existing web applications can be collaboratively browsed and used without limitations.

Croquet is a combination of computer software and network architecture that supports deep collaboration and resource sharing among large numbers of users within the context of a large-scale distributed information system. Along with its ability to deliver compelling 3D visualization and simulations, the Croquet system's components are designed with a focus on enabling massively multi-user peer-to-peer collaboration and communication.

Croquet's treatment of distributed computation assumes a truly large scale distributed computing platform, consisting of heterogeneous computing devices distributed throughout a planet-scale communications network. Applications are expected to span machines and involve many users.

In contrast with the more traditional architectures we grew up with, Croquet incorporates replication of computation (both objects and activity), and the idea of active shared subspaces in its basic interpreter model. More traditional distributed systems replicate data, but try very hard not to replicate computation. But, it is often easier and more efficient to send the computation to the data, rather than the other way round. Consequently, Croquet is defined so that replication of computations is just as easy as replication of data.

The Croquet 3D environment makes it possible for large numbers of people to enjoy shared telepresence, shared authorship of complex spaces and their contents, and shared access to network-deliverable information resources.

Delivery of slide presentations is available for synchronous or asynchronous delivery. Any presentation application can be used. Users can make presentations to one or more other users at the same time and show images or media objects to them while communicating with them through VoIP. Such presentations can be made to large audiences of users within a croquet space.

The Croquet team is also working toward the goal of providing full collaborative CAD capability. Users will be able to construct 3D objects and develop animations through Croquet's interface. The goal of these efforts is to make it possible for groups of users to get together and create high quality content in a collaborative way.

Croquet incorporates a high level scripting language which allows control of the objects that make up Croquet environments. Though this scripting language is ideal for relatively naïve users of the system, it is also designed to be used for virtually all high-level control and interaction.

Croquet utilizes an Open GL-based graphics engine and a semi-retained graphical engine pipeline, such that its rendering hierarchy is based upon dynamically compose-able objects, with each of these objects having full access to the OpenGL libraries.

Croquet is therefore both a complete development and delivery platform that enables people to carry out highly collaborative work.

The Croquet Project represents the combined visions of its principal architects: Alan Kay, Julian Lombardi, Mark McCahill, Andreas Raab, David P. Reed, and David Smith - all of whom believe that the time is right to bring to bear the underlying power of modern computers and connectivities.

The system probably owes the most to the efforts of Alan Kay and his colleagues at Xerox Parc that resulted in the birth of the personal computer, and more importantly, the idea of software as a tool for exploration and understanding. This was expressed as the Smalltalk-80 system that was focused upon extending children's ability to control their environments and express themselves via computer simulations. Croquet is built directly upon Squeak, the direct descendent of Smalltalk-80. David P. Reed developed the replicated computation model called TeaTime that it uses as the basis of the peer-to-peer real-time collaboration. The basic ideas behind it were first described in his thesis, and are fully developed here. David A. Smith developed the use of real-time 3D environments as the basis of Croquet's context based collaborative user interface. This approach included a component approach to world building, portals as a linking mechanism between these virtual environments, and video conferencing. Julian Lombardi and Mark McCahill developed architectures and server infrastructures that enable implementation of a scalable, massively multi-user system combining a grid computing architecture with a tier of decentralized servers to manage real-time interactions in a way that ensures accountability and trust relations among users. Julian brings to this effort his deep experience in exploring and implementing ways of coordinating and visualizing network-deliverable resources within collaborative 3D spaces while Mark brings his experiences developing one of the the first popular Internet e-mail clients (POPmail) for the Macintosh (and later the PC) and leading the Internet Gopher development group at the University of Minnesota.

TeaTime is the basis for Croquet's object-object communication and synchronization. It is designed to support multi-user applications that can be scaled to massive numbers of concurrently interacting users in a shared virtual space.

Croquet runs on all major platforms (Windows, MacOS, Linux) and requires a reasonable hardware graphics capability on your computer.

Croquet requires only a few tens of kilobits in bandwidth most of the time in order to achieve real-time collaboration. This efficiency is possible partly through classic P2P processing in which each client does rendering and any other possible calculations on its own.

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