in April 2010; but was pushed back to May 12, 2010, following a beta period. In addition to the Steam client, several features were made available to developers, allowing them to take advantage of the cross-platform Source engine, and platform and network capabilities using Steamworks. Through SteamPlay, the macOS client allows players who have purchased compatible products in the Windows version to download the Mac versions at no cost, allowing them to continue playing the game on the other platform. Some third-party games may require the user to re-purchase them to gain access to the cross-platform functionality. The Steam Cloud, along with many multiplayer PC games, also supports cross-platform play, allowing Windows, macOS, and Linux users to play with each other regardless of platform. Linux client and SteamOS Valve announced in July 2012 that it was developing a Steam client for Linux and modifying the Source engine to work natively on Linux, based on the Ubuntu distribution. This announcement followed months of speculation, primarily from the website Phoronix that had discovered evidence of Linux developing in recent builds of Steam and other Valve games. Newell stated that getting Steam and games to work on Linux is a key strategy for Valve; Newell called the closed nature of Microsoft Windows 8 "a catastrophe for everyone in the PC space", and that Linux would maintain "the openness of the platform". Valve is extending support to any developers that want to bring their games to Linux, by "making it as easy as possible for anybody who's engaged with usputting their games on Steam and getting those running on Linux", according to Newell. The team developing the Linux client had been working for a year before the announcement to validate that such a port would be possible. As of the official announcement, a near-feature-complete Steam client for Linux had been developed and successfully run on Ubuntu. Internal beta testing of the Linux client started in October 2012; external beta testing occurred in early November the same year. Open beta clients for Linux were made available in late December 2012, and the client was officially released in mid-February 2013. At the time of announcement, Valve's Linux division assured that its first game on the OS, Left 4 Dead 2, would run at an acceptable frame rate and with a degree of connectivity with the Windows and Mac OS X versions. From there, it began working