Video game actors represented by SAG-AFTRA rejected a final contract offer on Thursday from the trade association representing the video game industry, setting up the union’s members to strike at midnight Friday.

The actors were bargaining for a larger cut of royalties and limits on “vocally stressful sessions,” among other things. Negotiations broke down when the two sides couldn’t agree on royalty terms, reports Deadline Hollywood.

“We had hoped this would be successful,” said Scott Witlin, chief negotiator for the video game industry, “but union leadership left mediation without providing a counteroffer. We urged union leaders to put the package to a vote of their membership, but union leaders refused.”

The video game industry offered actors a 9 percent pay increase and up to $950 in extra compensation based on how many recording sessions for a game an individual took part in. A federal mediator was brought in on Wednesday to help the two sides reach an agreement, but was unable to bridge their differences.

Related Link: Video Game Voice Actors Consider Strike

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motion-capture actors in the multibillion-dollar video game industry receive an unequal portion of that revenue due to outdated contract terms.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

Related Link: SAG-AFTRA Threatens Video Game Publishers with Strike

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.

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

Technology reporter Garrett Reim can be reached at [email protected]. Follow him on Twitter @garrettreim for the latest in L.A. tech news.