When designer Adriaan de Jongh and artist Sylvain Tegroeg released Hidden Folks earlier this year, there was one piece of feedback that they heard plenty of. “A lot of people wanted more areas,” says de Jongh. “And a lot of people were very vocal about it.” The Where’s Waldo?-style game presents players with sprawling black-and-white scenes, and tasks them with finding characters hidden among the chaos with the help of succinct, sometimes obscure, clues. It’s cute and charming, with a level of interaction and playfulness that makes it a perfect fit for a leisurely afternoon with an iPad in hand.

After the game launched, de Jongh and Tegroeg set to work creating a brand-new factory level for players to tackle. It’s the biggest area in the game yet — with 3,400 interactive objects, more than 900 characters, and 28 targets to find — which is designed to give to players more to find, and add an extra challenge for the game’s dedicated following.

The process of creating any new level for the game starts with pen and paper, with Tegroeg sketching out ideas for new characters and scenarios. “He starts exploring on a little notebook he has,” explains de Jongh. “He starts drawing a bunch of stuff, separate elements, little scenarios that he puts together. And from that we extrapolate the sub-themes that we’ll put into the area.” Tegroeg then starts placing his creations in the game by hand, laying out the general structure of the level, before de Jongh goes in and starts adding interactive bits — which, in the case of the new factory, included a huge conveyor belt system. The two then go back-and-forth fleshing out each area with more detail.

With the new factory area, the idea was to create one huge space that was divided into smaller sections. There are loading bays and storage facilities, a parking lot and a cafeteria. Each area is distinct from the next, but still feels like part of the larger whole. This both makes it easier to tie hidden characters to specific areas, as well as ensure that players don’t find themselves lost in the sprawling factory. (It’s something the team had problems with in one of the original levels, the desert, in which players often lost their way scrolling through a massive expanse of sand.) It’s only after most of the level is already built that they starting hiding folks.

The goal is to place each target within a specific area. “It’s about making a thousand little stories in an area,” says de Jongh, “and then picking out some of them to highlight some of the cool things [Tegroeg] has been making.” From there it’s a very iterative process. Sometimes a hint might require some reworking of other parts of the level. For instance, one hint in the new level tasks players with finding a character sleeping in a pile of tires. But there are tires found in multiple parts of the factory, so the duo had to tweak the layout to make sure that the tires containing the sleeping character were more obvious.

The playtesting process for Hidden Folks is a bit more intimate than you might expect. Not only do players provide feedback for the levels, de Jongh also has them record their experience, and he watches every bit of footage, searching for areas that need to be tweaked. Sometimes it’s the wording of a clue, other times it’s a much bigger change like the shape of the map itself, but he always comes away with a long to-do list after watching a playtest. “It’s a big bloody mess,” de Jongh says of the process.

From there, the last thing is to sort out the order of the hints, which de Jongh says is done based on “pure intuition.” The goal is to strike a balance, alternating between easy and tricky hints. Though in the end, the order doesn’t end up mattering too much. “A lot of people, especially in the beginning, they try to go through all of the targets from left to right,” de Jongh explains. “And then later on — and I’ve seen this a lot in playtesting — people start reading all of the hints first, and then go through the level, so they can get a sense of what they’re looking for.” Creating the factory level took around two months of full-time work, double what the team initially anticipated.

Now that the new area is out — you can download it as a free update now — de Jongh says the pair are working on creating new content for the game, including a potential new water-themed area. They’re also hard at work on the much-awaited Android version, which will also be coming to China, where the game has proven surprisingly popular on Steam. (As some players have noted, Hidden Folks’ dense visual style bears a strong resemblance to the iconic painting Along the River During the Qingming Festival, which may partly explain its popularity in China.) Much like the factory update, any new additions to the game will likely be about addressing feedback from the vocal Hidden Folks community. Whatever happens with the game, though, there’s one thing players won’t see again.

“There’s one thing I’ll probably not do again,” says de Jongh, “which is put a giant button in the menu that says ‘New levels soon!’ That was a really dumb idea.”

Hidden Folks is available now on Steam, iOS, and Apple TV.