You mean apart from creating and still consistently updating CS:GO and DotA 2, which are both some of the most played games in the world?
Their "The Lab" VR demo, which is a collection of mini games, is also one of the most enjoyable VR experiences, so I'm very optimistic they can make something great again if they put their mind to it.
Yes, I mean exactly those games, which are neither new nor ground breaking, and which were originally authored by outside firms/contractors, not valve. Since then, most of Valve's additions to the games are in the form of monetization.
If you didn't notice the news articles, they even laid off almost all the people responsible for HL2 and its episodes, including the writer.
Valve has also released DOTA Underlords and Artifact in the two years. With HLA and Underlords Valve is actually releasing two games this year.