AUSTIN, Texas — Steps from a crush of scooters and throngs of tech hipsters munching on food truck fusion tacos, HBO has created another universe. Visitors talk in hushed tones and line up for the blessing of a woman in a long red gown. She whispers in their ear, and they quietly walk away, clutching the pin she's handed them, cast in the shape of the "hand of the throne," straight from the land of Westeros in "Game of Thrones." A robed chorus chants a familiar score astride an iron throne, protected by soldiers holding heavy spears, and shafts of light pierce the cavernous space. Just out the doors in the heavy Austin air, visitors are accosted by Wildlings wearing furs and shells, as a Khal Drogo look-alike threatens heavily armed "unsullied" warriors.

Visitors to HBO's SXSW activation are thrust into a realistic "Game of Thrones" simulation. HBO

This was the the most detailed and immersive of the many "activations" — or interactive brand experiences — we saw at this year's South by Southwest extravaganza, which runs through Sunday. Every March, brands across entertainment and social media come to Austin to reach influencers who are increasingly resistant to traditional advertising. Companies spend millions, with the price tags of these experiences seeming to shoot higher every year as they get bigger and more elaborate, with more food, alcohol and swag for fans.

Bleed for the Throne

Last year, HBO made headlines for its creation of a slice of "Westworld" just outside town. This year, the company tried to top itself with an experience that drew about 3,000 visitors over the course of three days in Austin. In addition to reminding visitors about the final season of "Game of Thrones" coming in April, HBO has teamed with the Red Cross to kick off a nationwide blood drive, which it's calling "Bleed for the Throne." A giant stained-glass red cross looms over the "Iron Throne," which was shipped in for this occasion.

HBO's "Game of Thrones" activation at SXSW 2019 was done in partnership with the Red Cross. Stephen Desaulniers, CNBC

Those who donate get a limited edition branded T-shirt — splattered with blood, of course — and a chance to win a trip to the show's season premiere in New York City. HBO went to great lengths to make the experience feel authentic until you step into a room full of Red Cross nurses with sterilized needles for blood donations. Some 80 actors were outfitted in costumes shipped in from the show's sets in Belfast. They don't break character, sticking to a roughly 100-page script created for them, and they even worked with a dialect coach. "We get the question all the time, how do you measure this?" Steven Cardwell, HBO's director of program marketing, said of the experience he spent six months working on. "For something like 'Game of Thrones,' we don't have an awareness issue. What we do have is a global blood shortage, and the idea is it's really not about impressions as a performance indicator, it's about lives saved." Cardwell says the Red Cross partnership is working. "We are seeing fans dress up in their favorite costumes or as their favorite characters coming into the drive to donate," he said. We are seeing a lot of first-time donors, ... a 40 percent uplift in new donors, and that's really the goal because it's a lifetime value proposition for these people. They can come back again and again and again, and even though this only happened for three days, there's a lifetime impact." HBO, which is now owned by AT&T, was joined by all its rivals for subscribers in the battle for attention. Netflix hosed a 1930s speakeasy-style bar, with poker, live music and a game to encourage visitors to take and share photos and compete to win prizes.

A burlesque scene from Netflix's activation at SXSW, which takes place in a 1930s-type speakeasy Netflix

To promote its Prime Original "Good Omens," Amazon took over a city block with a "land of earthly delights," featuring beer and wine, sushi, free manicures and even puppies. The space was designed with plenty of Instagram-friendly experiences, plus Snap filters branded with the show's logo, to spread the word via social media. "We need to do something that the customers will talk and will use social media, utilize social PR to help spread the word and extend our marketing just beyond traditional advertising," said Mike Benson, Amazon Prime Video's marketing chief. "Creating a unique experience here at SXSW is important because it's become such an influential audience that is vocal not just here in Austin but all over the world."

A scene inside Amazon's "garden of earthly delights," an activation at SXSW 2019 to promote the Prime Original show "Good Omens" Amazon Prime VIdeo