Anita Sarkeesian, a feminist cultural critic, has for months received death and rape threats from opponents of her recent work challenging the stereotypes of women in video games. Bomb threats for her public talks are now routine. One detractor created a game in which players can click their mouse to punch an image of her face.

Not until Tuesday, though, did Ms. Sarkeesian feel compelled to cancel a speech, planned at Utah State University. The day before, members of the university administration received an email warning that a shooting massacre would be carried out at the event. And under Utah law, she was told, the campus police could not prevent people with weapons from entering her talk.

“This will be the deadliest school shooting in American history, and I’m giving you a chance to stop it,” said the email, which bore the moniker Marc Lépine, the name of a man who killed 14 women in a mass shooting in Montreal in 1989 before taking his own life.

The threats against Ms. Sarkeesian are the most noxious example of a weekslong campaign to discredit or intimidate outspoken critics of the male-dominated gaming industry and its culture. The instigators of the campaign are allied with a broader movement that has rallied around the Twitter hashtag #GamerGate, a term adopted by those who see ethical problems among game journalists and political correctness in their coverage. The more extreme threats, though, seem to be the work of a much smaller faction and aimed at women. Major game companies have so far mostly tried to steer clear of the vitriol, leading to calls for them to intervene.