According to JJ Abrams, both Portal and Half Life movies are in development. When asked about the status of the rumored movies, Abrash said: "Not yet, but they're in development, and we've got writers, and we're working on both those stories. But nothing that would be an exciting update."
Valve received some pitches for Half Life movie before, but they were lacking in quality.
"Their stories were just so bad. I mean, brutally, the worst. Not understanding what made the game a good game, or what made the property an interesting thing for people to be a fan of."
Thanks PC Gamer