It was late into Zen Koi’s development when its lead developer Paul Naylor began to question what he and the team at LandShark Games were creating.

There’s never a good time for self-doubt, but this was a particularly inopportune moment: the studio, which he runs with his wife Kim, was on the verge of launching the casual collection game.

“Something that happens to game developers, or at least to me, is this crisis of faith,” Paul tells us. “You’ve put all this time and effort into making this experience for people. And you just suddenly start questioning: Is this actually good?”

Here, the couple tell us how that doubt was nearly the undoing of a game that’s now beloved by millions of players around the world.

Inspired by games such as Pocket Frogs and titles from the Pokémon series, Kim and Paul knew they wanted to make a collection game. They toyed with the idea of having to gather critters such as snakes, spiders and birds, before spotting the beautiful movements of some koi fish swimming in a pond near their home.

“We wanted to explore what makes this movement so specific to a creature that can be so mesmerising and relaxing to watch,” Kim, the studio’s creative lead, explains. That led them to the idea for Zen Koi, in which players grow, breed and collect gorgeous koi.

As lead developer, Paul wanted the organic movement of the fish to feel right. “The two inspirations for the koi movement were a game called Flow and a scientific research paper on creating a robotic swimming fish,” he says. Merging those two behaviours resulted in a smooth flowing and swimming motion for the koi that contributed to the meditative aspect of Zen Koi’s gameplay.

Kim based the appearance of the game’s koi on the unwrapping of the yin-yang symbol and created the sparse, serene underwater zen garden that gave the game its name.

Meanwhile Paul, a fan of role-playing games, made sure that the speed and agility of the koi could be levelled up in order to catch more difficult prey. “It builds the bond between the koi and the player a little more because the player’s putting time and effort into sculpting this koi,” he explains.

Paul also wove the idea of hit points into Zen Koi. The red plants in the pond not only slowed the koi down, but also damaged them. To restore health, the koi could eat the other plants that dotted the pond. But somehow it didn’t feel right.

“As we got more into the flowing nature of the movement and the zen spacing of the pond, we realised that those moments where you take damage are quite jarring to the experience,” says Paul, “so those things got knocked out.”

But with the removal of those elements, the game wasn’t entirely what Paul envisaged anymore – and that’s when the self-doubt crept in. “It was feeling less like a game and more like this experiential play around the pond,” he shares.

At that point the business reality of their situation had started to kick in. Neither Paul nor Kim were on the payroll for the company because it wasn’t affordable; the income from their first game Aviator was dwindling and whatever little funds they had from investors were also waning. That left them with only two options: call it quits or go ahead with the launch and see what happened. Kim encouraged Paul to choose the latter.

“Both of us have a different opposing sensibility that is kind of yin and yang in a way,” explains Kim. “He’s the eternal optimist and I’m the reality check. When we really have no time or money left, you have to make that tough decision.”

The pair had to have a difficult chat with their small team: Zen Koi was going to take a bit longer to complete and they were running low on money. Despite all this they embraced the zen nature of their game and launched.

It’s hard to imagine that what makes Zen Koi so compelling to its players today was also very nearly its undoing.

“The worst that can happen to your fish now is swimming through a red nettle plant, or near a red puffer fish, will momentarily slow you down,” says Paul. “The decision looking back now was an obvious move for Zen Koi, but at the time it was very scary, because we were worried players, without any threat of their koi dying, wouldn’t find the game interesting.”

Ultimately, Paul had to reframe his idea of fun to realise that Zen Koi could be a hit. “For me, it’s fun to have a difficult battle or challenging situation when playing a game,” he shares. “I hadn’t really given much thought to the idea of fun as a form of relaxation, as something that’s more just enjoying the moment.”

The game has had a greater impact than anyone on the team could have imagined. Among the reviews praising the relaxing gameplay are also players writing to them to say it’s helped them with insomnia and anxiety. The most memorable story came from a player who credited the game with helping him through panic attacks via an in-game support message. “We couldn’t believe that during a traumatic experience that someone would think to launch Zen Koi and play it,” says Kim.

Given that the Zen Koi that nearly wasn’t has been successful enough to spawn the sequel Zen Koi 2 and the collectors’ favourite Zen Koi Pro, Kim and Paul have much to feel good about. “Despite not knowing if Zen Koi would be a good game, it has managed to capture the attention of a global audience who appreciates its simplicity and meditative quality,” Kim says.

“I’m proudest of the fact we built something others love,” says Paul, “and I did it with someone I love.”