Has the official Gamescom site been hacked, and a fake PDF uploaded? We sure hope not, but boy are we wary of anything Half-Life 3.
Also of note, Dragon Age 3 appears on the list, as do lots of other (known) titles. We've reached out to both Valve and the Gamescom folks to see what's up, and we'll let you know as soon as we hear more.
Update: Valve's VP of marketing Doug Lombardi told Lambda Generation in July, "We will have the Steam team there to meet with developers and publishers. No game showing planned." Sorry, folks! We'll be sure to take a look around Valve's booth as soon as Gamescom opens officially tomorrow.
Update 2: Gamescom organizers characterized the listings for both Half-Life 3 and Dragon Age 3 as "a mistake," but wouldn't explain to Eurogamer why the listings appeared. The plot thickens!
Update 3: Valve rep Doug Lombardi reconfirmed with us that, "We are not showing any games in Cologne this year." Welp, that's that, folks. Unless it's not, of course.
Update 4: Gamescom's organizers tell us, "We can not officially announce it. Please check our list for further changes. Please see the legend for information about the sources."