The other three are payment processing company Vantiv Entertainment Solutions, Dreadnought publisher Greybox, and Taichi Panda developer Snail Games. With the introduction of these four companies, the ESA's membership rises to 32 companies.
"Our newest members are true industry innovators, leading the development of exciting new content and new opportunities to reach and engage consumers," ESA CEO Michael Gallagher said in a statement. "These highly creative companies represent the broad range of our industry's offerings, and we look forward to collaborating with them to move our industry forward."
id Software left the ESA in 2008 and was acquired by Bethesda a year later.
"ESA has a long-standing tradition of representing the computer and video game industry at the highest level on important policy issues," Bethesda owner ZeniMax Media CEO Robert Altman said in a statement. "We're proud to join the association that is the leader in promoting the development and growth of the video game industry."