A concept artist at Valve, Evgeny Evstratiy, has revealed that he was in a room where Half-Life 3 is being developed. He shared this information during the CG Voices podcast.
Evstratiy mentioned he wasn`t sure if he was allowed to talk about it, but stated that he visited a space where development was underway. However, he did not see the game itself:
Evstratiy has been working at Valve for several years. His work can be found in Deadlock, and according to the artist, he was involved in changing the visual style to the current version of the title.