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This is followed by "User" (green), "Known User" (orange), "Trusted User" (purple), and friends (yellow). When promoted to "New User" (blue) rank, they are given the ability to upload their own content using the VRChat SDK. All users begin at "Visitor" rank (grey). Users of VRChat are classified into various "trust levels", based on factors such as their use of the platform. In 2022, support for the Open Sound Control (OSC) protocol was added for more advanced interactions with external software and devices. A third-party compiler known as "UdonSharp" was developed to allow world scripts to be written in C#. While still considered alpha software, it became usable on publicly-accessible worlds beginning in April 2020. In 2020, a new visual programming language was introduced known as "Udon", which uses a node graph system. Some content has limitations in desktop mode, such as the inability to freely move an avatar's limbs, or perform interactions that require more than one hand. VRChat is also capable of running in "desktop mode" without a VR headset, which is controlled using either a mouse and keyboard, or a gamepad. Trends and variations of avatars spread through the community like memes, and avatars themselves are sold on places like booth.pm or given for free. Player avatars are capable of supporting lip syncing, eye tracking, and blinking, in addition to mimicking head and hand motion. A software development kit for Unity released alongside the game provides mechanisms for creating and uploading. Avatars and worlds are created and uploaded by its users, which require technical know-how. The game is made up of thousands of connected worlds, in which they can interact with each other through virtual avatars. VRChat 's gameplay is similar to that of games such as Second Life and Habbo Hotel.
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