games. Proton On 21 August 2018, Valve announced a new variation of Wine, named Proton, designed to integrate with the Linux version of the company's Steam software (including Steam installations built into their Linux-based SteamOS operating system and Steam Machine computers). Valve's goal for Proton is to enable Steam users on Linux to play games which lack a native Linux port (particularly back-catalog games), and ultimately, through integration with Steam as well as improvements to game support relative to mainline Wine, to give users "the same simple plug-and-play experience" that they would get if they were playing the game natively on Linux. Proton entered public beta immediately upon being announced. Valve had already been collaborating with CodeWeavers since 2016 to develop improvements to Wine's gaming performance, some of which have been merged to the upstream Wine project. Some of the specific improvements incorporated into Proton include Vulkan-based Direct3D 9, 10, 11, and 12 implementations via vkd3d, DXVK, and D9VK multi-threaded performance improvements via esync, improved handling of fullscreen games, and better automatic game controller hardware support. Proton is fully open-source and available via GitHub. WINE@Etersoft The Russian company Etersoft has been developing a proprietary version of Wine since 2006. WINE@Etersoft supports popular Russian applications (for example, 1C:Enterprise by 1C Company). Other projects using Wine source code Other projects using Wine source code include: OTVDM, a 16-bit app compatibility layer for 64-bit Windows. ReactOS, a project to write an operating system compatible with Windows NT versions 5.x and up (which includes Windows 2000 and its successors) down to the device driver level. ReactOS uses Wine source code considerably, but because of architectural differences, ReactOS code (such as DLLs written specifically for it, like ntdll, user32, kernel32, gdi32, and advapi) is not generally reused in Wine. In July 2009, Aleksey Bragin, the ReactOS project lead, started a new ReactOS branch called Arwinss, and it was officially announced in January 2010. Arwinss is an alternative implementation of the core Win32 components, and uses mostly unchanged versions of Wine's user32.dll and gdi32.dll. WineBottler, a wrapper around Wine in the form of a normal Mac application. It manages multiple Wine configurations for different programs in the form of "bottles." Wineskin, an open source Wine GUI configuration manager for macOS. Wineskin creates a wrapper around Wine in the form of a normal Mac Application. The wrapper can also be used to make a distributable "port" of