Update: While no explanation was given, gamescom organisers said Dragon Age 3 and Half-Life 3 appearing on the website was "a mistake".
The official website of gamescom has claimed that Half-Life 3 will be present at the show.
A list of all the titles that are due to appear at the show is showcased on the official site, with both Half-Life 3 and Dragon Age 3 mentioned. However, the following caveats are discovered when the page is translated:
Expected announcements gamescom 2012'. *Please take note of the sources: exhibitors, media, intenet forums, blogs. *no responsibility is taken for the correctness of this information.
Valve has been working on Half-Life 3 for several years but have yet to announce the game in any capacity. They have, however, stated that they're not done with lead protagonist Gordon Freeman's "adventures."