Harbourlight Studios spent two years building Gilded Depths, a slot that drops you onto the wreck of a 17th-century galleon off the Cornish coast. It combines a 6x6 grid with cluster pays, and every winning cluster feeds a pressure gauge. When the gauge fills, a diving bell carries you into one of three bonus rounds. The game is live now at TurboSven Casino, and we asked Marta Voss, the studio's head of design, how the team put it together.
We knew we wanted water. The team had sketched a few coastal ideas, and we kept coming back to the idea of a galleon wreck. Once we started researching shipwrecks along the Cornish coast, we committed to the setting. The diving bell arrived later, when we realised the bonus structure needed a visual way to move you between the three decks. Each deck needed to feel like a different room, and the bell was the natural way to move between them without any extra UI.
The first prototype used a simple win counter. It worked, but it didn't create any drama. We wanted a moment where the game shifts in front of you, so we built the gauge to fill with every cascade. The gauge sits in a brass housing at the top of the reels, and its needle ticks up with each win. Players told us in testing that watching the needle climb was half the fun, so we leaned into that. When it tops out, the bell drops and you pick a deck from a simple wheel. Each deck plays a different game: the Cargo Hold drops expanding wilds, the Captain's Cabin stacks multipliers, and the Crow's Nest turns the whole grid into a single respin sequence. The gauge also carries a risk element. You can cash out a smaller win from the gauge at any point, but if you push it to the top, you commit to the bonus round. That choice is where most of the tension lives.
We needed a character who could break the rules of the grid. Old Tom started as a sketch of a bearded figure in a sou'wester hat. He appears at random, picks a symbol, and turns every instance of it into a wild for that spin. He shows up about once every 150 spins on average, which keeps him special without making him a crutch. When he does land, you tend to walk away with a solid win. Testers loved him, so we kept him in. The sou'wester came from a photo one of our artists took on a trip to St Ives. We considered giving him a voice line, but a grumpy lighthouse keeper who never speaks felt more honest. Small details like that give the game a sense of place.
The response has been strong. Players picked up on the pressure gauge faster than we expected, which surprised us, because it's the most complex part of the game. The thing we hear most is that the Cargo Hold round exceeds expectations. We tuned it to be the most volatile of the three, and it shows. People who chase the big wins head straight there. The base game feedback has been more mixed, which we expected. Some players find the quiet stretches slow, but the ones who stick with it tend to be the ones who appreciate the payoff structure. We also see a lot of players sharing screenshots of the Crow's Nest respin, because the whole grid lighting up makes a good image. It's nice when a mechanic you built for function turns out to be the thing people want to show their friends.
The max win is 12,000x your stake, and the volatility is high. The RTP sits at 96.4%, which is above the current average for the market, and we held it there on purpose. You can play from 20p to £100 a spin. We wanted a game that rewards patience, so the big hits come from the Cargo Hold when the expanding wilds line up with a full gauge. That combination is rare, but when it lands, it lands hard.
It suits players who like cascading mechanics and don't mind waiting for the gauge to fill. The base game can run quiet for stretches, so if you prefer constant small wins, this isn't the slot for you. My advice is to start with smaller stakes and learn how the gauge behaves before you raise your bet. The game runs on mobile and desktop, and it works across all the major operators. Set a budget before you start, and if a session stops being fun, GamStop and BeGambleAware have the tools to help you step away. The Gambling Commission regulates the UK release, so you get the usual protections that come with a licensed operator.
Our composer recorded a real diving bell and layered it over a ticking metronome. The idea was that every cascade keeps time, so the music speeds up as the gauge fills. When the bell drops, the brass comes in and the metronome stops. We wanted the audio to tell you where you are in the game without you having to look at the screen. We also recorded the creak of a wooden hull and used it as a low ambient layer under the base game. It's subtle, but it keeps the nautical setting present even during quiet spins. The bell sound is the one players mention most, which is satisfying, because we recorded it in a harbour in Falmouth and it took three days to get right.
Balancing the three bonus rounds. One round can dominate the numbers, and then the other two become dead content. Our math team spent months tuning the hit rates so each deck has a distinct risk profile but a similar expected return. The Cargo Hold is the high-volatility option, the Captain's Cabin sits in the middle, and the Crow's Nest is the steady one. Getting that balance right took longer than building the game itself, and it's the part we're most proud of.
We built the grid to work on a phone screen first. The gauge sits at the top of the reels, and the deck selection is a simple swipe. Most of our players are on mobile, so we designed the layout around a thumb. The desktop version came after, and it was a matter of scaling up the artwork.
We have ideas. There's room to expand within the three decks, and we've talked about a sequel that takes the diving bell deeper, past the galleon into the trench below. We haven't confirmed anything yet, but we enjoyed building this one, and we want to return to it. Beyond that, the studio has two other titles in production, one in a different setting altogether. We don't want to be a one-world studio. The game is rolling out to more operators over the next few weeks, so the audience is still growing. If the numbers hold up, we'll be back in that trench before long.