Valve has reportedly been playtesting a game called HLX, believed to be Half-Life 3, for the last few months. These tests now involve family and friends, not just other development teams. The practice is similar to what happened during the development of Deadlock, where changes led to its art style being reworked twice over two years, and Half-Life: Alyx, which was delayed into 2020 for script rewrites.
Half-Life fans have made progress on a Black Ops expansion, much like Opposing Force and Blue Shift. It’s also been revealed that Jay Pinkerton and Erik Wolpaw are writing for HLX after leaving the company in 2017. The game is said to be far along in development, with improved physics, destructible NPCs, and an upgradeable HEV suit.
Gabe Follower believes that if the project passes the New Year holiday without major issues, it could be announced as early as next year. However, Valve has not officially revealed HLX, so it’s essential to take these leaks with a grain of salt. Still, the combination of recent playtests and previous comments from Valve suggests a strong possibility of an announcement in 2025.
Source: https://www.thegamer.com/half-life-3-hl3-playtests-begin-leak