It’s not a nerd prom without a little disappointment. Geek Bar Beta in Chicago’s trendy Wicker Park neighborhood was planning a blowout for the “Game of Thrones” season premiere this month.

There were going to be costumes and product giveways and televisions showing the premiere of HBO’s fantasy drama. This was the first opportunity Geek Bar, which opened in October, had to show a live “Game of Thrones” episode, so the free party was promoted on Facebook to attract new customers.

But it also attracted the attention of HBO, which sent a letter March 27 to Geek Bar, telling the bar not to show “Game of Thrones” at its April 12 premiere party because HBO shows are not allowed to be screened in public.

“It’s like they’re thumbing their noses at geeks,” Geek Bar owner David Zoltan told the Tribune. “The geeks are the core audience. Without the geeks, ‘Game of Thrones’ would have never gotten this far.”

Geek Bar is not the only establishment to be told “Game” over. HBO has cracked down on bars that have aired episodes of its bloody drama, including a Brooklyn bar that received a cease-and-desist letter from HBO last week.

HBO spokesman Jeff Cusson said HBO is a pay subscription service that “should not be made available in public establishments. When it does happen, it is of particular concern when there is an attempt by such places to profit off of programming on the service.”

It’s unclear how many Chicago bars show “Game of Thrones” to their customers.