Valve has previously said it's working on new games though what that was beyond its already announced Artifact project remains to be seen. What we do know though, is that it's taking on new people to work on these new projects.
To get a hold of some of the top-tier employees Valve is looking for, it has a brand new job site under its belt where you can read about all of the stipulations and qualification demands it has for all potential new employees. There it has job listings for writers and game designers, with the former requiring experience in entertainment mediums or as copywriters, as well as a dedication to collaborative projects and "the drive to apply your expertise as a writer to everything we do."
That's most notable because Valve has had some high-profile writers leave its employ in recent years. Combine that with its search for new game designers and it seems clear that Valve is looking to work on some new, exciting projects.
Other job listings it has on its site include art, audio design, business development, data science, facilities, finance, hardware engineering, legal, product design, software engineering and technical infrastructure. With all of its Steam money pouring in, it seems as if Valve is expanding in just about every direction, but it's very clearly looking to build games as part of that expansion.
For a look at all of the jobs that Valve is hiring for, check out its dedicated jobs page here.