Most everyone believes that Georges died in World War I... While he may not have died in the war, he, as a legend, died with the war.
Hugo was designed to be shown in 3-D, which, when done well, can make audiences feel like they're part of the action or even give them a sense of peril. The movie also pays tribute to the early days of film, when moving pictures such as A Train Arrives in the Station and The Great Train Robbery were shockingly realistic to viewers. One scene shows audiences jumping in their seats to avoid a train that is seemingly coming toward them.
The movie's tagline is, "One of the most legendary directors of our time takes you on an extraordinary adventure." It seems like this is supposed to be emphasizing Martin Scorsese's involvement to sell tickets, but when you think about it, it could also be referring to the "legendary filmmaker" Georges Méliès, since so much of the movie revolves around the "emotional journey" caused by his movies, and he ends up setting most of the plot in motion.