Quick answer: During a GameSoundCon Q&A, Valve composer Mike Morasky mentioned HLX alongside Deadlock, the first time a Valve employee has publicly used the name of the rumored project. He didn't say what HLX is or when it's coming.
A Valve developer has said "HLX" in public. Composer and audio artist Mike Morasky was on a GameSoundCon 2026 panel called "Valve's Approach to an Open and Flexible Audio Engine," alongside sound designers David Feise and Carlye Nyte. During the Q&A, he was asked about managing voice counts and brought up how Valve's HDR audio system plays into it.
"In fact, I think Deadlock has their own version of HDR," Morasky said. "HLX has its own version, so on and so forth." According to PC Gamer and GamesRadar, Feise appears to whisper "nice work" right after, then wraps up the answer by saying groups are "its own one-hour talk." PC Gamer also reports that at the end of the panel, Feise told him, "Good job, you only said HLX once."
HLX isn't a new name. It has turned up in datamined Source 2 code for years, including in Counter-Strike 2 and Dota 2 updates, and fans have long tied it to a possible new Half-Life game. VideoCardz says this looks like the first time a Valve employee has used the name in public.
What it does and doesn't tell us: HLX is a real name used inside Valve, not one the community made up, and it apparently has its own version of the HDR audio setup. Morasky didn't say what HLX is, didn't confirm it's a Half-Life game, and gave no release timing. Valve hasn't announced anything. The full panel is available to watch on Vimeo, according to PC Gamer.