Marc Laidlaw is a former employee at video game and digital distribution company Valve Corporation, whom are reponsible for the online gaming platform Steam as well as many popular single-player and multiplayer video games.

Laidlaw is reponsible for most of the story-writing in the popular Half-Life video game franchise. In particular, Laidlaw wrote the stories for Half-Life, Half-Life 2, Half-Life 2: Episode One and Half-Life 2: Episode Two as well as spin-off games such as Portal, Half-Life: Decay and Half-Life: Uplink.

Laidlaw intended to write the story for Half-Life 2: Episode Three, a sequel to Half-Life 2: Episode Two that was due to release during Christmas of 2007 but the game was delayed multiple times and still to this day has not been released.

Laidlaw confirmed his resignation from Valve and retirement from video game writing on January the 8th, 2016.

On August the 25th, 2017, Laidlaw released a blog post detailing what appears to be the planned story and events that were supposed to occur in Half-Life 2: Episode Three.