A bit of mysterious code might indicate Valve is working on a Half-Life VR game for its Vive headset.
A few bits of code for "HLVR" were recently found in a new DOTA 2 update, and this could be Valve's way in communicating with its community without making any sort of official announcements. "HLVR" code has been found many times in the Destinations Steam VR app, and its believed the HLVR code is linked to Valve's experimental in-house VR prototype made of Half-Life assets that was used to test out the Source Engine's limits in VR.
According to the DOTA 2 update source code, the HLVR code is specifically "used to force the HLVR player to speak", hinting that the Half-Life VR game (if it's indeed real) will have some sort of dynamic interactivity with players. It's interesting to see any mention of this source code in DOTA 2 especially since it has nothing really to do with DOTA at all.