Video game actors represented by SAG-AFTRA are threatening to go on strike Friday if demands for a larger cut of royalties and limits on “vocally stressful sessions” are not enacted.

The union argues that voice and motion-capture actors in the multibillion-dollar video game industry receive an unequal portion of that revenue due to outdated contract terms.

“The videogame employers we are striking continue to operate under the terms of an agreement structured more than twenty years ago for an Industry that was only beginning to utilize professional performances,” SAG-AFTRA wrote in a statement. “Since then, games have evolved to provide increasingly immersive and cinematic experiences that compete with television and theatrical motion pictures for consumer dollars.”

SAG-AFTRA is also asking for a mandate that video game producers disclose more about the characters they are asking actors to portray, as well as increased use of stunt coordinators on motion-capture work.

Contract negotiations between the union and Interactive Video Game Publishing Companies, which represents video game developers, have been ongoing for the past 18 months.

The publishing group argued, in a statement, that a strike would be counter-productive for union members.

“We consider the Union’s threatened labor action to call a strike precipitous, unnecessary and an action that will only harm their membership,” the organization said in a press release. “SAG-AFTRA represents performers in less than 25 percent of the video games on the market. Any strike would not only deny SAG-AFTRA’s membership work, but this would also give their competitors, who do not engage union talent, a leg up while any strike would be in place.”

Companies that could be impacted by the strike include Activision Publishing Inc., WB Games Inc., and Disney Character Voices Inc.