Source 2

[3] At the 2014 Game Developers Conference, Valve employee Sergiy Migdalskiy showed off a Source 2 physics debugging tool being used in Left 4 Dead 2.

[4] Source 2 was first made available via Steam Workshop tools for Dota 2 in 2014 prior to it being officially announced at the 2015 Game Developers Conference.

[1][6][7][8] Valve also stated that it would support the Vulkan graphics API and use a new in-house physics engine called Rubikon, which would replace the need for the third-party Havok tools.

[13][14][15][16] Reborn was first released to the public as an opt-in beta update that same month before officially replacing the original client in September 2015, making it the first game to use the engine.

[21][22] The engine also supports the creation of games in virtual reality, being used in SteamVR Home, the Robot Repair tech demo within The Lab, and Half-Life: Alyx.