"Easter eggs" have become common in visual media, whether it's film, television, or video games. Creators hide these bits of surprise in a way that's findable to those with a keen eye and an appreciation for whatever the Easter egg makes reference to.

As games evolved over generations, the principle behind the Easter egg has grown exponentially, with more iterations on the concept appearing in modern video games.

One recently released game that leans into the idea of Easter eggs is Zombie Army 4: Dead War, Rebellion's latest in the series, which maintains a cult following. Jordan Woodward, lead level designer at Rebellion, is no stranger to the implementation of secrets within the game world. Much of what infuses a sense of charm into the world of Zombie Army is the carefully positioned Easter eggs, which encourage players to carefully dissect each level. A conversation with Woodward gave insight into the process behind it all.

Horror Movie Inspirations

Within the early moments of Zombie Army 4, a small room presented a dead end with nothing of interest but a typewriter. With no other means of interactivity in the room, the typewriter beckons players to inspect it. Choose to do so and it will begin to type on its own accord -- reeling off numerous horror movie quotes for the player. Then, as the player turns around, a greeting from several creepy dolls is glaring back at them, startling the player.

It’s a game series that’s built around the love and admiration of classic horror movies -- especially the golden age of the genre.

“The franchise and universe of Zombie Army take a lot of inspiration from cult horror and 80s B-movie horror films and that vibe is definitely a big part of Zombie Army 4,” said Woodward. “They are genres a lot of the team are massive fans of, and they had a lot of fun coming up with references and Easter eggs from their favorite films to put in the game. We had feedback from our community, and this was one of the things people loved about the franchise, so it was an obvious fit for Zombie Army 4 too.”

Looking at player feedback and how the community reacts is an integral part of the process, as well as looking back at past installments. “Creating an engaging and intriguing world which players want to explore was at the core of designing the levels and lore within the game,” Woodward said. “The humor and tongue in cheek delivery of that additional layer was something previous Zombie Army games in the franchise were praised for and another reason our fans, and ourselves, loved the other games. We wanted to revisit this in Zombie Army 4, continuing with the trend of adding movie references and quirky Easter eggs to discover, to drive some more exploration and provide a few chuckles along the way.”

With so many different voices in the team at Rebellion, everyone had their own ideas for what to implement in the finished release. “A lot of the development team are big fans of the horror genre and we spent a lot of time watching cult zombie horror movies such as Dead Snow, Outpost, and Overlord - so naturally everyone jumped at the chance to get their favorite zombie and horror movie references in to Zombie Army 4.”

Having the player recognize these secrets isn’t integral to the experience. It was to be made clear that finding such extras was an extension to the overall experience. “It was also our aim to provide players with a layer of depth and environmental storytelling that is always present for the player to find but wasn’t crucial to the enjoyment of the game,” Woodward said. “It’s a game that doesn’t take itself too seriously, but lore-wise everything still makes sense within the world and story we’ve created.”

And that world is crafted around a love for horror movies with a vast array of inspirations. With examples stemming from influences such as The Shining, and the more recent Netflix show Stranger Things. In Zombie Army 4, the game references Stranger Things via an environmental puzzle: lights lay draped on the wall, each dangling beside a letter. Figuring out the correct sequence in which to shoot the lights rewards players with a locked safe opening, which is filled with an assortment of items to assist them on their quest.

Conjuring Secrets

When such a large team is working on a project of this magnitude, there must be a degree of preparation when it comes to implementation. The early stages of development called for the team to come together, collaborate on ideas, and see what sticks.

“In the pre-production stages of development and during development, we encouraged everyone from the team to submit as many ideas as they could for their favorite Easter eggs, movie references, horror references and even references from previous Rebellion games,” Woodward said. 

With such a wealth of ideas coming from a large team, it’s no doubt that many would fail to see the light of day. Collectively discussing the plethora of concepts the team had brainstormed and choosing what to go forward with was a key aspect of the thought process.

“After we had collated a huge list of ideas, we started to look at which ones we wanted to take forward, prioritizing them and how and where we wanted to present them. Also, what would be the most fun way to discover it?” Woodward explained. “We then started to pin down the locations where we thought each of them would work well and the designers mocked them up in the levels using pre-made or whitebox assets and our in-house Asura Engine scripting tools for any triggering logic.”

While Zombie Army 4 is jam-packed with Easter eggs bursting from the seams, the development team still had plenty of ideas which inevitably were left unfinished. According to Woodward, this was the case with this development cycle. 

“A few ideas had to be scrapped from the list,” he said, "mainly due to complexity or time it would have taken to create them as some would need bespoke complex animation sequences or custom art assets we didn’t have the time to make. Or we had to simplify the reference, using different assets we already had. A lot of the coolest ideas made it into the game, though.” 

Designing the Easter egg

With so many hidden secrets packed into one game, a balancing act needs to be performed to ensure that they’re tucked away from the casual player, but not too obscure for the keen eyed. Often, the Easter eggs that lay dormant in Zombie Army’s world lay waiting at the end of offbeat tracks or incorporated into heavily decorated rooms, waiting for eagle eyed players to stumble across their presence.   

“The design approach with Easter egg placement was to encourage curious exploration of the game world,” Woodward said. “Often, we didn’t want to lead players directly to them, as this may have caused an unwanted distraction from the main objective of the mission or an encounter, this being especially problematic in co-op.

“The balance was to create areas and paths that weren’t too far away from the main play areas and main paths, so players didn’t get lost and could always quickly find their way back to a fight. These additional areas helped add some extra depth to the world and make the world seem larger and more open to explore.”

Sometimes, the balancing act can be tricky business and finding that perfect contrast into seamlessly integrating Easter eggs into the world of Zombie Army isn’t as easy as it may seem. 

“There were some tweaks we had to make to some of them to make them more obviously connected with a different part of the level,” Woodward said. “For example: the gas rats Easter egg in the Hellbase mission. During playtesting players weren’t getting the link between finding and killing the rats in the level to open a locked safe in the following room. We tweaked this and put tiny gas masks on the rats and a rack for tiny gas masks to hang on the wall in the safe room by the safe. A mask would be hung on the rack each time a rat was killed to show how many were found. It’s subtle, but it helped make the link.”

The sheer amount of creativity Woodward and the team put into Zombie Army is evident through the playful level design they’ve crafted. Much of the process has been rewarding, but Woodward has found the most enjoyable part being the developers' playtesting sessions. 

“What I’ve personally enjoyed most about seeing all the awesome Easter eggs, environmental storytelling pieces and references is the creativity and enthusiasm from the design team. Even now during internal play sessions the team are finding references in each other’s work they didn’t know about!”