Great Blue slot review

Great Blue slot at a glance

Great Blue is an undersea slot from Playtech, released in 2013. It keeps to a familiar five-reel, three-row frame with 25 paylines, and puts its personality into one feature: a free spins round you shape by picking shells.

A 96.03% RTP is in line with many modern slots. High volatility tells you the free spins carry much of the game’s value, so the base game can feel slow between triggers.

How the features work in Great Blue

The whale wild

The killer whale is the wild. It substitutes for every symbol except the scatter and doubles any win it helps form. So a line combination worth 30p on its own pays 60p when the whale completes it.

Pearl clam scatters and the free spins

Landing three or more pearl clam scatters starts the free spins. You begin with eight free spins at a 2x multiplier. Before they play, you pick two shells from a selection, and each pick either adds more spins or raises the multiplier.

That means two players who trigger the same round can end up with quite different set-ups: one with more spins at a lower multiplier, another with fewer spins at a higher one. The game shows the totals before the spins start.

Retriggers

If the scatters land again during the round, you get 15 more spins at the same multiplier. How the whale’s doubling combines with the free spins multiplier is set out in the game’s paytable, so read it there rather than assuming.

The Great Blue shell pick on a touchscreen

On a phone, the shell pick is a simple tap on two of the shells. It feels like a decision, and it’s enjoyable as one, but the shells’ contents are set by the game’s random number generator. No shell is luckier than another, and nothing about your earlier spins changes what’s behind them.

Picking a particular position, tapping faster or waiting before you pick has no effect on what you win. The game’s published RTP already includes every possible pick result.

Playtech uses a similar choose-your-bonus idea in Halloween Fortune, where you pick a witch for the number of free spins and a potion for the multiplier. If you enjoy that format, it’s worth comparing the two.

Great Blue in pounds: RTP, stakes and a £20 budget

With a 96.03% RTP, the house edge is 3.97%. Multiply what you stake in total by 3.97% and you get the long-run expected cost: about 79p on £20, or £3.97 on £100.

Over an hour, the picture depends on pace. The table below assumes 400 paid spins an hour, a round number chosen for illustration (UK rules allow no more than one spin every 2.5 seconds).

High volatility means real sessions stray far from these averages in both directions. Treat them as the price of play, and set a deposit limit that matches what you’re happy to spend.

Playing Great Blue on iPhone and Android

Great Blue’s 5×3 grid suits a phone screen, and the shell pick translates naturally to taps. It runs within UK casino apps and in mobile browsers; the app’s own layout decides whether it opens in portrait or landscape. Set-up help is in our guides to iPhone casino apps and Android phone casino apps.

1. Sign in to a UK-licensed casino app and search the lobby for “Great Blue”.
2. Open the game and tap the paytable or information button.
3. Read the free spins rules and confirm the RTP shown in the game.
4. Pick your stake, keeping the hourly cost table above in mind.
5. Spin with a tap each time; UK apps don’t offer autoplay on slots.

If the game freezes mid-round, don’t panic or start a new spin straight away. Our page on what happens if your app crashes mid-game explains what to check and who to contact.

Playtech, the studio behind Great Blue

Playtech was founded in 1999 in Tartu, Estonia, by Teddy Sagi. It’s headquartered in Douglas, Isle of Man, and listed on the London Stock Exchange under the ticker PTEC. It’s known for the Age of the Gods jackpot slots and its live casino studios, and it has owned Quickspin since 2016 and Eyecon since 2017.

You can read more on the Playtech company website (opens in a new tab), or see our page on Playtech slots on mobile for its other games, including Age of the Gods and Buffalo Blitz.

UK limits that apply to the Great Blue slot

Great Blue is subject to the same Gambling Commission rules as every online slot in Britain:

• A maximum stake of £5 per spin for over-25s and £2 for 18 to 24-year-olds, set out in the Commission’s online slots stake limit guidance (opens in a new tab).
• Spins can’t complete in under 2.5 seconds, and turbo or slam-stop buttons aren’t allowed.
• No autoplay, in force since 31 October 2021.
• No celebratory sounds or graphics when a spin returns your stake or less.
• Your net spend and time played displayed in real time (since 17 January 2025).

Feature buy-ins are not offered to British players since a Gambling Commission warning in January 2020. Our game design rules page covers the background.

Ocean slots like Great Blue

If the sea theme and wild-doubling appeal, two older Novomatic games follow a similar pattern. Figures are from each developer’s published specifications.

Great Blue has the highest published RTP of the three. Read our Dolphin’s Pearl Deluxe review and Lord of the Ocean review, or browse every game in our mobile slot reviews.

Great Blue slot verdict for mobile players

Great Blue is a tidy, readable slot with a free spins round that gives you some say in its shape, even though the outcome stays random. It suits players who like classic line slots and can live with high volatility.

Great Blue casino apps in the UK

Playtech games appear in many UK lobbies, but each casino picks its own range, so search for Great Blue before signing up. Our partners’ welcome spins are for selected slots rather than this game. All are 18+, for new customers, and terms apply.

• PlayOJO: first deposit of £10 or more for 80 free spins on Big Bass Bonanza, at 10p a spin. There’s no wagering, so winnings are paid in cash. Excludes Northern Ireland; through the designated link only; can’t be combined.
• Coral: after a deposit (certain types excluded), bet £10 or more on slots to get 100 free spins on selected games worth 10p each. They must be accepted within 48 hours and used within 7 days. No wagering on winnings. Runs 1 October 2026 to 1 February 2027.
• Ladbrokes: deposit and spend £10 or more on slots to get 50 free spins a day for 10 days (up to 500) on selected games at 10p each. Claim each day before 23:59 and use within 7 days; no wagering. PayPal, Skrill, Neteller, Paysafe, Moneybookers and prepaid card deposits don’t count.

Spin values work out at £8, £10 and up to £50, but they’re stake values rather than cash, and returns from them vary. More options are in our best slot apps ranking.

18+. Every casino game has a built-in house edge, so over time you should expect to lose what you stake. Set a budget before you play and stop when it’s gone: safer gambling tools and support. Free, confidential help: National Gambling Helpline 0808 8020 133.