For people who don't play city builders, it may be easy to look at them as something mechanical and bureaucratic. Grids of streets, well-ordered manufacturing production lines, and carefully tailored catchment areas to ensure residential zones will efficiently staff nearby businesses, don't scream the stuff of life. Though, play enough of them and you will often see there can be a good deal of living going on at street level. Zoom in close on Cities: Skylines and you can follow people as they travel to work, hover over your town in Anno 1800 and you watch the carts take goods from the harbours to factories to markets to the doors of your townspeople.

Life Below may not be about constructing a city exactly, but this underwatcher cosy city builder still captures that sense of bustling life.

At the start of Life Below, you take on the mantle of a newly minted Guardian, a water sprite tasked with restoring life to a stretch of bare sea floor. You've a few worker sprites with you that you can send out to long-dead coral and reclaim some coral matter and pearls, the resources you'll need to grow out your reef. You're soon placing Sprout Coral and Clams, which your sprites will travel between to harvest resources and bring back to your Reef Heart for storage.

For the production buildings to function, you need to place Moon Coral nearby that link them to the Reef Heart. It's effectively a little underwater power grid. Life Below may look like it's aiming for a more natural take on city building but there are aspects to it which are SimCity simply dressed up in scuba gear.

However, as you expand your reef there are elements of the game that do make it distinct from surface level city builders and make it more akin to Zoo Tycoon. Your reef isn't only to be enjoyed by water sprites, you are growing it to attract and house wildlife. So, you are soon researching seagrass lures, algae coral, and sea anemone, which draw in clownfish, increasing your reef's biodiversity – a resource you use to research new technologies and expand the landmass upon which you can spread your reef. The fish will only come if you've created the environment for them to thrive. For simple clownfish, that means they need enough algae. Though more demanding wildlife will want a finer balance of resources.

I've only been playing the Life Below demo, but there are hints of how balancing the needs of the ecosystem will be a challenge. After all, there aren't many games with a HUD icon devoted to the water's PH level. Each coral you place impacts the acidity and temperature of the water around it. Some of the structures' descriptions hint at how this can get out of hand, with coral algae threatening to bloom and sprawl if you don't have enough wildlife in the area to keep the fauna in check.

For all the threat of a dying ocean, boiling with an explosion of plant life, Life Below is a wonderfully cosy city builder. I've found myself just watching the warming sea above my coral reef infrastructure, where schools of clownfish lope about in easy circles. When I started Life Below, this small square of ocean floor was a scrap of rock with nothing living there. Now there's patches of algae, vibrantly coloured corals, and sprites buzzing between it all like bees in search of pollen. Little details, like how if you click the sea floor, it kicks up a little dust and any fish swimming nearby dart away from you, as though you just tapped the glass wall of an aquarium.

If you're looking for a city builder to sink into, I'd recommend giving the demo a go. It's not world-changing, but it is charming.