Cryptocurrency titan Coinbase turned heads on Sunday with its first-ever Super Bowl ad, which featured a QR code bouncing around the TV screen similar to an old DVD screen saver.

Scanning the QR code took people to the Coinbase website, where new users could get $15 in free Bitcoin and existing users could sign up for a $3 million sweepstakes.

Chief Marketing Officer Kate Rouch wrote in a blog post Monday that more than 20 million people tried to access Coinbase within a minute, overwhelming the site and causing some to be unable to do so.

The throwback approach stood out on a night when most ads were packed with celebrities. While the 60-second ad had its online detractors—some of whom compared the deluge of crypto ads to the barrage of dot-com ads in 2000, right before the dot.com crash—the Clio Awards named it the best ad of the night. The Clios are selected by a jury of advertising experts.

The ad, produced by Accenture Interactive, got people chattering on social media and received coverage across the media landscape, from CNN to The Washington Post.

It was the latest bold move for Coinbase, which has grabbed headlines over the past year for a variety of reasons, from publicly criticizing the U.S. Securities and Exchange Commission to seeking to soften its intense work culture by shutting down for a week each quarter.