The Surprising Predictions
Sword Art Online is a landmark franchise that spawned an entire genre of anime, but it was actually predicted by Yu-Gi-Oh! on two separate occasions. Of course Yu-Gi-Oh! isn't the only anime to have played with its concepts beforehand. However, it is shocking that the series would have predicted it in this way given the two shows are in entirely different genres.
Yugi and his friends in the virtual world
Sword Art Online is a series following Kirito, a gamer who gets trapped in a virtual reality game and must battle his way through in order to escape. As the series progresses, he plays other virtual reality games as well, and in each one manages to master the game he plays and complete whatever goal is set up for him. This premise inspired many other shows to copy this idea, with a myriad of other similar series proliferating in the years since Sword Art Online premiered. However, before that series became so popular, Yu-Gi-Oh! actually featured the idea of traveling into a virtual world as well.
Noah in a virtual chair in Yu-Gi-Oh
Yu-Gi-Oh! and Virtual Reality
Between the Duelist Kingdom and Battle City arcs, there was a strange storyline that featured Yugi and his friends entering a virtual reality game to rescue Kaiba, who had been trapped within it. Later right before the finals of the Battle City tournament, Yugi and his friends were again trapped in a Virtual Reality game, this time by Kaiba's digitized stepbrother. This arc also let Kaiba overcome his trauma in a brilliant way. Both of these arcs of course had some major differences with Sword Art Online as the nature of the games was very different and Yu-Gi-Oh! didn't present these storylines as a power fantasy. But there are some major similarities as well.
Distinctive Paths
Despite the similarities, Sword Art Online isn't a Yu-Gi-Oh! rip-off. The later anime took the premise in a very different direction than its predecessor did and was also extremely different in themes and tone. However, it does show that many modern ideas can have their roots in the most unexpected places, given as a whole Sword Art Online and Yu-Gi-Oh! are quite different from each other.