Well, the back story of the Cordyceps infection in 'The Last of Us' is quite complex. It seems to be a sort of apocalyptic scenario where the Cordyceps fungus, which originally might have only infected insects, adapted to infect humans. This could have been due to environmental changes or some random genetic mutations. Once it started infecting humans, it spread like wildfire, taking over the bodies and minds of those it infected. The infected then became a threat to the remaining uninfected humans, leading to the post - apocalyptic world we see in the game.
The Last of Us was not a comic originally. It was first developed as a video game, which gained significant popularity and later inspired other related media, but the comic came later.
The duration of the story in The Last of Us depends on several factors. If you rush through the main quests, it could be around 12 hours. But if you take your time, do side quests, and explore the environment thoroughly, it could stretch to 25 hours or more.
Well, it's quite important. This side story enriches the whole narrative. For example, it might show some events that were only hinted at in the main plot. It can also introduce new elements to the world - building of 'The Last of Us'. Maybe it reveals some secrets about the infected or the post - apocalyptic society from a different perspective, that of Ellie and her friend, which is really cool and makes the whole game world feel more complete.