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Detective 221b Slot - Review, Free & Demo Play

Detective 221b
Detective 221b
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Updated: 22.07.2025
Reviewed by: Joe Booth
Detective 221B is an online slot provided by Mobilots. This Sherlock Holmes-inspired game was released on 13/02/2019 and it features moving Wilds, the Free Spins round, and a Bonus game. In our review, we will tell you more about these bonuses as well as discuss the game’s RTP and volatility. You will also have an opportunity to try the slot’s demo absolutely for free.

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In this review
  1. Slot details
  2. Theme
  3. Bonus Rounds & Free Spins
  4. Summary
  5. Where to play
General information about Detective 221b slot

General information about Detective 221b slot

Rating by Joe Booth:
7.9
User’s Rating: (based on  reviews):
0.0
Mobilots
Write a review +25 SJ points
  • Release Date:
    13.02.2019
  • Volatility:
    Medium
  • RTP:
    97.0%
  • Multiplier:
    No
  • Max. win:
    500x
  • Bonus game:
    Yes
  • Free spins:
    Yes
  • Scatter Symbol:
    Yes
  • Wild symbol:
    Yes
  • Symbol Stacked:
    No
  • Jackpot Game:
    No
  • Slot lines:
    30
  • Slot reels:
    5
  • Layout:
    5-4
  • Stakes range (€/£/$):
    1.5 to 150
  • Slot Theme:
    Detective
  • Technology:
    JS, HTML 5
More infoLess info

How to Play

To start your gaming session, please follow this list:

  1. Load the game
  2. Click on the triple-bar button to access the menu
  3. Check the paytable and read the game’s rules
  4. Click on the Bet button to set your wager
  5. Press Spin and enjoy

Detective 221b is a 30-payline slot that has a 5x4 reel layout. The bets can go between €1.5 and €150 in this game while the top prize is worth 500x your stake. The game features an array of bonuses including Free Spins, a scratch card Bonus game, Scatter, and Wild symbols. The wins are formed by combinations of 3 or more matching symbols on the payline.

The Autoplay and Turbo spin buttons are handy in case you’d like to speed up or automate the gameplay.

Detective 221b RTP and Volatility

9 
This detective slot game has a medium volatility level and an RTP rate of 97%.
Detective 221b slot has a balanced math model. this is a medium volatility game with a return-to-player rate set at 97% which we find a very good combination. The medium variance level suggests that you’re likely to experience plenty of moderate wins throughout gameplay and it won’t be too hard to trigger bonuses. The RTP of 97% rate is above the industry’s average and refers to the amount of cash you can expect to receive in payouts for every €100 spent on bets.

Theme

8.8 

This video slot has a mystery theme and it’s based on Sherlock Holmes and his companions from Baker street who are solving crime puzzles in Victorian-era London. The game offers players to join the legendary detective and help him track down the villain.

The game is set in the dark streets of London and has a mysterious soundtrack that perfectly pinpoints the most significant events during gameplay. The reels are set on the wall of the old house illuminated by the pale street light.

The beautifully-drawn reel symbols have cartoon-like graphics and feature four characters as well as 10-A card royals. The themed symbols include Dr Watson, a villain wearing a top hat, a beautiful lady, and Sherlock Holmes himself. The detective’s symbol is the most valuable icon in this slot.

Violin is Holmes’ favorite musical instrument and it acts as a Scatter that triggers free spins. A pistol is the game’s Bonus symbol that unlocks an exciting Bonus game. The magnifying glass represents the Wild. This symbol can help create bigger winning combos by substituting any of the other game symbols except for Scatter and Bonus.

Theme
Detective 221b slot paytable

Mobile Compatibility

Detective 221b slot mobile
Detective 221b is an HTML5 slot optimized for the best performance on all portable devices. Of course, you can also play this game in any web browser on your PC. The game supports all operating systems, so you will be presented with high-quality graphics and engaging gameplay on any device of your choice.

About Mobilots

Mobilots is an innovative software developer creating online casino games of various genres. The company offers an impressive portfolio of high-quality games optimized for mobile play including online slot games, instant sports, and video poker games.

Mobilots is a team of experienced developers, mathematicians, and graphic designers who live to brainstorm, design, develop, and release their products in the international iGaming market. Many Mobilots games have become fan favorites, and the company keeps up expanding its library of titles with the goal of getting to the next level. With such an incredible creative team and a sizable portfolio of exciting games, Mobilots has all of the needed ingredients to succeed.

Some of the well-known online slots from this provider are Honey Money, Gemmer, Halloween Toons, Diamond Bar, Advent Wins, Bitcoin Bob, and Candy Cash.

Bonus Rounds & Free Spins

7.8 

Moving Wild

When the moving Wild symbol lands on the grid, it will move one step from right to left on every spin until it reaches the first reel.

The moving Wild will remain visible and active for your next session until it completes its journey even if the game is closed before the Wild reaches reel 1.

Bonus Game

If three or more pistol Bonus symbols land on the reels, the scratchcard Bonus game gets unlocked. This feature provides instant win prizes, which may boost your payouts considerably. You will have to scratch the hidden symbols with a coin to reveal your prize. The game comes to an end if the revealed symbol is a villain.

Free Spins

The violin Scatter can trigger the game’s Free Spins round. Three Scatters award 5 free plays while 4 and 5 violins will grant you 10 and 20 free spins, accordingly.
Detective 221b slot Free Spins

Detective 221b Demo Play

You can try out the free demo of Detective 221b here, on our page. You won’t have to sign up, just load the demo and test the slot’s gameplay using the free credits to wager. You will have a chance to evaluate the game and its bonus features without risking any of your cash and decide whether this game is a good choice for you.

Max Win

6 

The game’s top possible win is equal to 500x your bet.

This medium volatility game offers a discouraging max win of only 500x of the bet. The paytable wins are relatively low and you’d have to play with the higher bet level to get some decent wins. Look out for Sherlock Holmes symbols that are the most generous icons on the paytable and can boost your balance if you land a bigger winning combination.

Overall Rating

7.9
If you’re a fan of detective stories and are eager to prowl the streets of London looking for the villain, this Sherlock Holmes-themed game from Mobilots will certainly give you a lot of enjoyment. The exciting Bonus game, the Free Spins round, and moving Wilds will help to enhance gameplay and break from the base game routine. The game’s weak point is a low winning potential, but its medium variance and an RTP of 97% can guarantee plenty of small wins.
Hits
Perfect balance between RTP and variance
Bonus game and free spins
Moving Wilds
Misses
Max win is only 500x
No gamble
High minimum bet

Detective 221b Slot - FAQ

What is the most valuable symbol in Detective 221b?

Sherlock Holmes is the game’s highest-paying symbol.

What is the RTP rate of Detective 221b?

The game has a solid RTP of 97%.

Does the Detective 221b slot have a jackpot?

Unfortunately, this slot doesn’t have any jackpot prizes.

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Joe Booth
Joe Booth
Expert in: News, Blog, Slot reviews, Payments
Joe is an expert online casino player, who knows all the tricks and tips on how to get to the most massive wins. He is also an experienced online casino games reviewer, with hundreds of written articles behind him, on all kinds of online casino games. He makes sure to play them, see how they work, and then gives his honest expert opinion about them to other players, our readers. 

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Reviewed by Editor-in-Chief
Nikita Lukanenoks

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