
An impossible locked-room murder: Captain Mortuga lies dead beside an ancient cauldron aboard the world’s strangest submarine, crewed by sketchy suspects. A handcrafted point-and-click with sharp humour and tricky puzzles. Dive into the next mystery from the creators of Tangle Tower & Crow Country.
Modeled estimate, not a reported figure. How we estimate →
Prices
The United States storefront in every case, so this compares stores and not countries.
Prices
Each in the currency that store quoted — not converted: the gap between two rows is the publisher's pricing, not an exchange rate.
Every market we collect.
About
In the pitch-black waters beyond a long-abandoned fishing town, the enigmatic captain of the world's strangest submarine has been murdered. Some say he was an immortal time-traveller. Others say he was a vampire, cursed to stay hidden beneath the waves forever...
Found alone in a locked room, with only an ancient stone cauldron to suggest how he might have died, it's up to Detective Grimoire and Sally to piece together what really happened. Was it a curse, released from the cauldron? One of the submarine's eccentric crew? Or does the bizarre truth run even deeper...
• Every clue is a fully realised 3D object waiting to be examined for hidden secrets
• Grimoire and Sally are back, and joined by a fully voiced cast of mysterious suspects
• A hauntingly beautiful original soundtrack performed by the Budapest Art Orchestra
• Explore every hand-painted inch of The Mortuga Submarine, where not all is as it seems...
*Voice audio is only in English
Genres
Sums Steam only; PlayStation publishes no volume signal, so the true total is higher by an unknown amount.
| Store | Price | Audience | Score | Chart | Est. revenue |
|---|---|---|---|---|---|
SteamYou are here | $19.99 | 2.9Kreviews | 99% | — | $1.1M |
| $19.99 | 69ratings | 96% | — | not modelled |
Matched by title — a reused name can pair the wrong games. * is a critic aggregate. Prices and positions are each store's United States storefront; Epic charts worldwide. Audience and Score too, except Steam's, which is worldwide.
Engagement
Reviews
Themes across 1527 recent reviews and how positive each mention is. A keyword signal, not full sentiment analysis.
Reviews
Great game all around. Very satisfying mystery,
Absolutely lovely presentation all around, with a very fun mystery to unravel, I was hooked right up to the very end
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Media

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Price dynamics, follower growth, revenue and sales trajectories with interactive tooltips
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Stats
All-time low is the lowest price we've recorded for this game since we started tracking it.
Languages: English*, French, Italian, German, Spanish - Spain, Japanese, Korean, Portuguese - Brazil, Russian, Simplified Chinese, Spanish - Latin America, Traditional Chinese*languages with full audio support
Hours played at review time, across 1.5K reviews with recorded playtime.
positive critical· bar length = how often the theme comes up
SFB continues its line of comedic deduction games with The Mermaid Mask, and they deliver on all fronts. From a murder mystery, Grimoire and Sally are treated to a cast of whimsical characters, all delivered with great effect by the voice cast. Knowledge of the previous games aren't required, but this game does make quite a few callbacks to their previous cases, particularly Tangle Tower. Fans of this series should easily find something to like here, and getting to the end of the case is worth a lengthy investigation.
A great continuation for the series! Makes some nice additions from previous games and was a thorough treat to play. The characters and voice-acting were superb
This game only continues to build on the Detective Grimoire series' history of perfecting the point-and-click and mystery formats. The game is visually stunning, its gameplay is rich and satisfying (every clue you can find prompts unique dialogue from each of the suspects - lots to discover there), and the mystery is turn-screw tight. I think everyone should play this game. I cannot overstate how much the game being fully voice acted brings to it as well. The cast adds many new dimensions to their characters and colors how you receive information about the world. I feel I could write a whole essay about the setting of these games, both the small worlds they occupy and the background world as a whole. I won't do it here, but suffice it to say Mermaid Mask once again pulls off a fascinating network of character dynamics with some of the most realistic, nuanced characterization I've seen
As a longtime fan of the Grimoire series, I've been happily waiting for this game's release ever since it was announced. Now that it's here, I can say wholeheartedly that this is probably Grimoire's best adventure yet. This title has twists and turns that take you all over the Mortuga submarine, searching for clues about Captain Mortuga's untimely death and his relationship with everyone onboard. I really love the animation and art direction, because even underneath the sea there's a lot of color and charm to be had within the submarine's rooms. Having played Tangle Tower before this, I really enjoy how this title takes the foundation of that title and just builds upon it in every way. There's lore callbacks to the previous entries in Grimoire's tales, as well as harder puzzles and better pacing, especially near the end. Every character has lovely music and voice acting to go along with them, really solidifying their personalities and relationships with each other. I love the banter between Sally and Grimoire; as always their sharp wit made me laugh a lot. If you are at all interested in point-and-click adventures or mystery games, give this a try! And if you happened to really like this title, it may be worth it to go back to Tangle Tower or Secret of the Swamp.
It's good, in an obvious way :)
This game was fun, artful and challenging. The characters were creative, funny and unique. There's a lot to remember. I recommend writing down clues to combine with the repository of clues in the game. This game can be played as a group (in person), too. I will buy more games from this developer!
The artstyle is gorgeous, the writing is wonderful, the mystery is well-organized, and it's the third entry on Steam of my boy Detective Grimoire! You want to play this game! But you *really* want to play Detective Grimoire (Secrets of the Swamp) and Tangled Tower first! Preferably in that order!
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Active players
Estimated daily and monthly active players (DAU/MAU) modeled from peak concurrency.
Players by region
Where this game's players are, estimated from review languages.
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