Employees of Activision Blizzard, the video game company that produces World of Warcraft and Call of Duty, staged a walkout Wednesday morning to call for better working conditions as the company faces allegations of a “frat boy” culture and severe harassment and discrimination against female workers.

The California department of fair employment and housing (DFEH) filed a lawsuit against the company last week after a two-year investigation found widespread sexual harassment, retaliation and discrimination and that the video game maker “fostered a sexist culture” in which female employees earn less than males doing similar work.

Just 20% of Activision Blizzard’s 9,500 employees are women, and leadership at the company, one of the largest video game makers in the world, is largely white and male.

Hundreds of workers gathered outside the company’s headquarters in Irvine, California, Wednesday morning while others, unable to attend in person, took part in a virtual protest.

The protest also drew solidarity efforts from non-employees, including video game streamers and eSports teams, who announced they would not post on social media for the duration of the walkout to show their support.

Organizers of the walkout are demanding the company “improve conditions for employees at the company, especially women, and in particular women of color and transgender women, non-binary people and other marginalized groups”.

Activision Blizzard employees are also calling for an end to mandatory arbitration in employee contracts, which prevent workers from taking conflicts with their employer to court, policies to improve representation of women and marginalized groups, the publication of salary data, and an audit of the company by a diversity, equity and inclusion taskforce.

In response to the allegations, the company initially said the lawsuit contained “distorted, and in many cases false, descriptions of Blizzard’s past”, Polygon reported. A letter sent to staff from a company vice-president last week described the lawsuit as “truly meritless and irresponsible”. Since then more than 3,100 current and former employees signed an open letter expressing their support for the DFEH lawsuit, according to NBC News.

“We no longer trust that our leaders will place employee safety above their own interests,” workers wrote. “To claim this is a ‘truly meritless and irresponsible lawsuit,’ while seeing so many current and former employees speak out about their own experiences regarding harassment and abuse, is simply unacceptable.”

On Tuesday, the company’s CEO, Bobby Kotick, apologized for the company’s “tone deaf” response to the lawsuit and promised swift action.

“I want to recognize and thank all those who have come forward in the past and in recent days. I so appreciate your courage. Every voice matters – and we will do a better job of listening now, and in the future,” Kotick wrote to workers in a letter posted to the company’s website.

The company has asked a law firm to review its policies and procedures to “promote a respectful and inclusive workplace” and Kotick said it would immediately bring on additional staff to investigate claims from employees, hold listening sessions, evaluate managers and company leaders, address hiring practices and make changes to inappropriate in-game content.

A spokesperson said the company supported the workers’ right to walk out, and is committed to change.

“We are fully committed to fostering a safe, inclusive and rewarding environment for all of our employees around the world. We support their right to express their opinions and concerns in a safe and respectful manner, without fear of retaliation,” the spokesperson said. “We know there are a variety of topics that need to be considered. The leadership team at Activision Blizzard is also committed to long-lasting change, listening, and continuing the important work to create a safe and inclusive workplace that we can all be proud of.”

On Wednesday nearly 500 current and former employees of Ubisoft, the publisher of the Assassin’s Creed game, signed a letter in support of the Activision Blizzard walkout and condemned how their own employer dealt with sexual misconduct, Axios reported.

“It should no longer be a surprise to anyone: employees, executives, journalists, or fans that these heinous acts are going on. It is time to stop being shocked. We must demand real steps be taken to prevent them.”