Greentube slots

What is Greentube and who makes Greentube slots?

Greentube is the online gaming arm of the Austrian Novomatic Group. The business began in 1998, took the Greentube name in 2000 and became part of Novomatic in 2010. It is headquartered in Vienna and has a UK office in Nottingham. Alongside slots, it supplies video bingo, video poker, table games and social casino products.

What sets it apart from most studios in our slot providers hub is where its best-known games come from. Many began life as Novomatic cabinets on casino and arcade floors before being adapted for screens, so Greentube is as much a converter of proven machine designs as an originator of new ones. Our page on Novomatic slots covers the parent company’s own history.

From casino floor to screen: Greentube, Novomatic and the UK

Novomatic was founded by Johann Graf in 1980 and built a large presence in British gaming venues. It bought Luxury Leisure in 2014 and the Talarius and Quicksilver outlets in June 2016, rebranding them as Admiral, and took its controlling stake in Greentube in 2010. In 2019 it sold Novomatic UK’s Gaming Technology Group, including the Astra Games business that built Category B, C and D machines, to Inspired Entertainment.

That background explains the look of Greentube’s catalogue: ten-line games with simple symbols, scatter-triggered free spins and familiar fruit layouts. If you have used machines in an adult gaming centre, some of these themes may look familiar, but the online versions are different products with their own maths. Land-based machines are grouped by the Gambling Commission’s gaming machine categories (opens in a new tab), with Category B3 allowing £2 stakes and £500 prizes and Category C £1 and £100; online slots sit outside that system and follow the online stake limits instead.

Best-known Greentube slots and their published figures

Each has a page of its own: Book of Ra Deluxe, Lord of the Ocean, Dolphin’s Pearl Deluxe, Lucky Lady’s Charm Deluxe and Sizzling Hot Deluxe. The Diamond Link series is also among the studio’s best-known products, but we don’t hold verified figures for it; check each game’s help screen.

How a classic Greentube slot machine is built

Most of these games follow a compact formula: five reels, three rows, ten lines and a scatter that starts free spins. The difference lies in what happens inside the bonus.

• Book of Ra Deluxe picks one symbol to expand across whole reels during free spins, the design described in our guide to book slot machines. Its very high volatility rating comes from that feature: most of the game’s return is concentrated in rare expanded-symbol rounds.
• Lord of the Ocean and Dolphin’s Pearl Deluxe apply the free-spins formula to an underwater theme, both rated high volatility.
• Lucky Lady’s Charm Deluxe uses a ten-line layout with a scatter-triggered bonus; sources differ on whether to rate it medium or high volatility.
• Sizzling Hot Deluxe is the plainest: five lines of fruit and sevens, closer in spirit to a classic slot machine than a feature-led video slot.

Our Book of Dead vs Book of Ra Deluxe comparison shows how a newer studio reworked the same book idea with a higher RTP.

Greentube RTP: why the figures run lower than many online slots

Greentube’s best-known titles publish RTPs of about 95.1% to 95.66%. Many newer online studios publish defaults of 96% or more. The gap looks small but changes the average cost of play. Our explainer on RTP sets out the theory; the table shows the effect in pounds.

In other words, on average, £100 of play on Book of Ra Deluxe at 95.1% costs £1.40 more than the same play on a 96.5% game. Within a single session that difference is swamped by volatility, but over many sessions it adds up. Our page asking what a good RTP for a slot is puts these numbers in context.

Greentube max wins at UK stake limits

Only two games in our checked data have published caps, both at 5,000× the stake, and Book of Ra Deluxe’s figure varies between sources. Here is what 5,000× means at the stakes UK players can use; the £2 limit for 18 to 24-year-olds and £5 limit for those aged 25 and over are explained on our online slot stake limits page.

A cap is the most a game can pay on one spin or round. It says nothing about how often large wins happen, and on very high-volatility games such as Book of Ra Deluxe the typical session ends well below the stake.

Greentube’s UK licence and regulatory record

Greentube’s remote gambling software licence is Gambling Commission account 41020, and it also holds a Malta licence (MGA/CRP/120/2006). You can check the account on the Gambling Commission’s register of gambling businesses (opens in a new tab).

A separate group company, Greentube Alderney Limited (account 39050), runs a consumer casino under the Admiral Casino name. In January 2025 it agreed to pay £1 million under a regulatory settlement after the Commission found social responsibility and anti-money laundering failures, including affordability limits that were not fully based on customers’ income and delays in spotting signs of harm. The Commission’s announcement (opens in a new tab) notes it was the company’s second action, after a £685,000 payment in 2021. The settlement concerned the operator business, not the way Greentube’s games are built or tested.

How to check which Greentube version you are playing

Book of Ra Deluxe exists at 95.1% and 94.26%, so the version a casino runs matters. These steps confirm it.

1. Open the game and press the paytable or information button.
2. Page through to the game rules at the end.
3. Read the stated theoretical return to player.
4. If it shows 94.26% rather than 95.1%, the casino is running the lower version.
5. Check the stake range at the same time; online games must stay within the £5 or £2 limits that apply to you.

Greentube and Novomatic slot myths

• ‘The online Book of Ra is the same as the machine in the arcade.’ They share a theme and look, but online and land-based versions are separate products with their own maths and limits.
• ‘Old-style games are easier to win on.’ Simpler layouts don’t mean better odds; these games publish lower RTPs than many modern titles.
• ‘Stopping the reels early improves the result.’ Online, the outcome is fixed by the RNG when you press spin, and UK rules have banned slam-stop on online slots since 31 October 2021. See is stopping the reels a skill?
• ‘A long losing run means the book is due.’ Every spin is independent of the last.

Are Greentube slots worth it? Who they suit

These games suit players who like a simple, traditional layout and understand the higher average cost. If you want the book mechanic with a higher published RTP, compare the alternatives in our guide to high RTP slot machines.

Where to play Greentube slots online in the UK

Greentube games are not something we can track casino by casino, and line-ups change. Search for Book of Ra Deluxe or any other title at Coral, Ladbrokes or PlayOJO.

The offers below are not Greentube promotions. Coral gives new customers 100 free spins worth 10p each on selected games after they deposit and bet £10 on slots. Ladbrokes gives 50 free spins a day for 10 days (up to 500) at 10p each after a £10 spend on slots. PlayOJO gives 80 no-wagering free spins on Big Bass Bonanza with a first deposit of at least £10. All are for over-18s, and terms apply.

18+. Gambling should be entertainment that costs money, not a way to make it. Decide a budget before you play: plan a slot budget. Free, confidential help: National Gambling Helpline 0808 8020 133.