According to ex-Valve writer Chet Faliszek, Left 4 Dead president and co-founder Gabe Newell didn't want to put zombies in the game.
As initially reported by NME, Faliszek recently spoke with YouTube channel Kiwi Talkz, where he spoke about a variety of topics, including his work on Portal, The Anacrusis, and more. Most notably, host Reece Reilly asked Faliszek about the work he did on Left 4 Dead, in particular how zombie stories can often have a number of clichés and there's little room for something original sometimes. Which led to Newell pushing the team away from zombies, initially.
"At the time, once I went to dinner with Gabe and he was like 'if you look at zombie movies, Night Of The Living Dead is about racism, Dawn Of The Dead is about consumerism'" said Faliszek. As part of the conversation in trying to understand the core concept of what Left 4 Dead might be, Newell asked "what is your game about?"
"And I'm like well it's about working together, it's the game itself, it's a reflection of the game," Faliszek continued. "We'd kind of get pushed more and more because I remember [Newell] said 'well let's not do zombies, zombies are just cheesy.' At the time you did not have The Walking Dead TV series and all of this, so it was very cheesy."
Faliszek explained how he watched a lot of these classic horror films when he was younger, not realising how some of them are a bit cheesy, so in turn made the decision to make the characters more conscious of the environment they're in.
"So I was just like why don’t we just take the characters and the world, and make some of the characters in the world aware that they’re in a zombie movie essentially. Zoe and Lewis understand that like 'oh my god this is the thing from movies,' but they play it seriously."
Considering the reason why everyone plays Left 4 Dead is the co-op gameplay against horde of zombies, it's probably a good thing that no one listened to Newell on this particular occasion.