It’s not every day that a video game comes along and single-handedly changes the face of the industry, but on November 19, 1998, that’s exactly what happened. That game was Half-Life, a staggeringly ambitious PC shooter from Valve Corporation that opened developers’ eyes to a world of new possibilities.

In the documentary below, youtuber ‘Liam Triforce’ gives you the the full background story of the Half-Life universe. It’s almost two hours long, so prepare with popcorn and sit back, because you’re in for a jolly ride down memory lane.