Infestation Survivor Stories (previously known as The War Z) Executive Producer Sergey Titov has penned a post-mortem on Gamasutra about the game's launch in 2012, noting how inviting the comparison to DayZ worked against the project.
"That said, The War Z was a terrible choice of name, as it naturally invited comparisons between our game and DayZ," Titov admitted. "We made a big mistake in not listening to the vocal minority of our community who thought the name was terrible [...] Beyond not listening to the community, we were also very arrogant in our public communications. We should have taken more care to communicate how and why this was not a DayZ clone, citing specific differences in both design and conception. Instead of saying to ourselves 'Oh well, haters gonna hate!' we should have tried to understand where the hate was coming from and address it."
Another key mistake that Titov and his team made was engaging in an "arms race" to get The War Z to Steam before DayZ, which resulted in its being yanked from that platform due to misrepresentation of the existing game features. Even with these missteps, Titov said that Infestation sold 2.8 million copies, and of those, over half logged at least 50 hours of playing time apiece.
You can read Massively's hands-on impressions of this title from 2013.