Steam’s policy quirks ended up working against the developers.
A demo version of the Team Fortress 2 Classic mod had been slated to appear on Steam in October. During the submission process, however, an unwelcome issue came to light that neither the mod team nor Valve’s reviewers had noticed.
It turned out that Steam does not allow an application to be classified as both a mod and a demo simultaneously, so the demo release was cancelled:
“In the final stages of review we were informed that an app on Steam cannot be both a mod and a demo. Unfortunately, neither EMINOMA nor Valve caught this until last Saturday, because the initial reviews did not flag it as a problem and led us to mistakenly believe we could proceed with the release.”
The full release of the Team Fortress 2 Classic mod on Steam is still planned — its store page is available here.
Source: iXBT.games