I don’t mean the concept of media based on video games in general. That has existed since the 80s and is obviously still going on strong today, stronger than it’s ever been even with things like the Last of Us TV show.

I mean expanded universe in the old Star Wars sense where the comics, novels, etc. were taking place in the same continuity as the games, though unlike with Star Wars, EU fluff could be as important to the overall canon as the actual games themselves. I feel like this practice reached its height in the Xbox 360 generation, mainly influenced by the success of the early Halo novels and then mostly died off afterwards.

Dead Space, Mass Effect, Gears of War, Mortal Kombat, Halo and many more all had spin-off media fleshing out the universes of those games. More power to you if you like reading video game novels and comics but I mostly thought reliance on external media allowed video game writing to be even worse than it already tended to be, the 343 era of Halo being a prime example