It seems the closest thing we are going to get to a new Half Life game is either leaked nuggets of a Half Life 2: Episode Three script, Black Mesa, or... this.
Before Cayle George began enjoying his role of Principal Game Designer at Guerrilla Games, he was a Senior Designer at Valve, working on games like Team Fortress 2 and Portal 2. You may have heard of them.
Looks like in his spare time, Cayle has been thinking about his old digs and what it may be like to dabble with the Half Life universe and so we have Half Life: Caged. Caged is a total conversion of the original Half Life, which means if you own HL1, you can download Caged absolutely free.
If that wasn't exciting enough, synthwave genius Lazerhawk provided the soundtrack, as seen in the below trailer.