Valve began making comics for Team Fortress 2 way back in 2009. They began as a series dedicated to providing lore and teases for major new updates that were coming out for the class-based competitive multiplayer shooter.
In 2013, Valve eventually kicked off a new series of Team Fortress comics that told an ongoing story of the eternal war between Red and Blu, the hunt for Australium, and just generally provided a ton of added in-universe...