SAN DIEGO — A woman clad entirely in white greeted me with a robotic smile and a warning. “This may be disorienting,” she said. “Are you O.K. with that?” Inside a nearby display case were Old West weapons, including a sawed-off shotgun and a bowie knife. “Please select one,” she said brightly.

And so began my trek through “Westworld: The Experience,” an HBO marketing stunt that sums up both the promise and the challenges of Comic-Con International, which kicked off its 48th installment here on Thursday.

Comic-Con started in 1970 in a hotel basement, attracting about 300 comic book die-hards. This year, 167,000 people are expected to attend an event that sprawls across downtown San Diego and focuses on what it calls the “popular arts” — television shows, movies, video games and comics.

Hollywood has long seen the fan gathering as a crucial marketing opportunity. But Comic-Con’s epicenter, the San Diego Convention Center, has now grown so chaotic and overcrowded that many movie and television companies complain that it is hard, if not impossible, to stand out. The blinding hubbub, combined with the ever-increasing power of social media, has led many studios and networks to focus more intently on elaborate experiences — “activations,” in industry shorthand — in the surrounding hotels and streets.