It's not just Half-Life fans who are waiting for a project with a "3" in the title.
The team-based shooter Team Fortress 2 continues to be popular and attract players. However, Valve no longer supports it as actively as before, and content is supplied by the community.
Perhaps Valve still intends to return to the franchise. Well-known blogger-insider Tyler McVicker stated that he is sure that Team Fortress 3 is in development:
"[At Valve] they are working on a new Team Fortress. Now we have more evidence that the [TF] team is not only still together, the project continues to develop, and game development is progressing."
Dataminers drew attention to the new features that Valve added to the Source 2 engine and the mention of the code name "TF". Judging by the code, developers will be able to transfer assets from the current Team Fortress 2 to a conditional TF 3.