3 screenshots which was simply a thread with three screens from Half-Life 1. From the logos at the bottom of the poster, it looks like the poster has been paid for by spieletipps and GIGA games.

Half-Life 1: Source, Day of Defeat: Source, Valve's back catalog on Steam, a complete Prima strategy guide, three different Half-Life 2 posters, a Half-Life 2 hat, a Half-Life 2 postcard ...

There’s a huge poster along the convention center’s facade that is seemingly advertising Half-Life 3, the Moby Dick of PC games. Neither site has commented on the ruse thus far, instead ...

Unfortunately, if you’re a fan of the Half-Life series then you’ll still have to wait until Valve makes the official announcement for the third installment. Instead of the game, this poster ...