Space slots

What makes a space slot

A space slot is set beyond Earth's atmosphere or borrows from science fiction: planets, galaxies, rockets, alien creatures, star maps and constellations. The genre leans toward bright neon colours on dark backgrounds, which suits games where many small symbols fill a large grid.

That visual fit is one reason space themes so often come with cluster pays grids. Where a fruit or Egyptian slot usually sits on five reels and some paylines, a space game is just as likely to drop you onto a 7×7 board. For other themes, see our slot themes hub.

Space slots compared: RTP, volatility and max win

Figures come from developers' published specifications or our checked data. If a figure isn't in our data, check the game's help screen.

Release years: Cygnus 2019, Reactoonz 2 and Star Clusters Megaclusters 2020, Rocket Reels September 2021, Gigantoonz 2022, Starburst Galaxy 2024. Starburst's gem symbols also make it a regular on our gem slots page.

Space slot grids: what the numbers mean

Grid games are easier to compare once you count the positions. A 7×7 grid holds 49 symbols, an 8×8 grid 64. In a cluster game, more positions give clusters more room to form, but the game's maths is tuned so the RTP stays where the studio sets it. A bigger board isn't a better deal by itself.

Cygnus shows how ways to win grow: each extra row multiplies across all six reels, so going from four to eight rows takes the count from 4,096 to 262,144. Star Clusters Megaclusters starts smaller, on a 4×4 grid, and expands as symbols split, a mechanic explained on our split symbols page.

Reactoonz, Reactoonz 2 and Gigantoonz: do sequels pay more?

Play'n GO's alien grid games are the backbone of the genre, and their figures make a useful point. The original Reactoonz lists 96.51%. Reactoonz 2's top version lists 96.2%, and Gigantoonz's top version 96.25%. The sequels changed the features and, in Gigantoonz's case, the board size, but they didn't raise the return.

The ceilings moved around too: 4,570× for Reactoonz, 5,083× for Reactoonz 2 and 4,000× for Gigantoonz, which pays clusters with cascades on its 8×8 grid. All three are rated high volatility. Our page on whether new slots are better than old slots looks at the same question across the market, and Play'n GO has more on the studio.

Space slot costs and max wins in pounds

Here's the average cost of 600 spins at 25p, which is £150 in total stakes, worked out as stakes × (100% − RTP). Individual sessions will land well above or below these figures.

Apart from the 94% version, these games sit within about £1 of each other on £150 of stakes, so volatility will shape your session far more than RTP. The exception is a lower-RTP version, which is why the help screen is worth a look. Our slot RTP guide explains how versions work.

Space slots for steady play or big swings

• Low: Starburst, with a 500× cap and frequent small wins.
• Medium: Planet Moolah, a 25-line game from WMS.
• Medium–high: Cygnus and Star Clusters Megaclusters.
• High: Reactoonz, Reactoonz 2, Gigantoonz and Rocket Reels, where long quiet patches are normal.

On a £20 budget, 10p spins give you 200 goes and 50p spins just 40. On the high-volatility grids, 40 spins can easily pass without a meaningful win. See how long £20 lasts on a slot for worked examples.

Space slot myths: chain reactions and 'charged' grids

Grid games with meters and charging features can look as if they're building toward a payout. They aren't. Every spin's result is decided by a random number generator, and the Gambling Commission's RTS 7 standard on random outcomes (opens in a new tab) sets requirements for how those outcomes are generated.

A meter that resets between spins carries nothing forward, and a long run without a feature doesn't make one more likely next time. Where a game does carry something over within a feature, the help screen says so. Our slot myths page covers other common beliefs, including timing and 'hot' machines.

How to play space slots online

1. Choose your budget and set a deposit limit before you start.
2. Open the help screen to see the grid size, how clusters or ways pay, and the RTP for this version.
3. Match the volatility to your budget: lower for longer sessions, higher only if you accept long dry runs.
4. Pick a stake that gives you a sensible number of spins.
5. Watch the net spend and session time shown on screen.
6. Stop at your limit; don't increase stakes to recover losses.

UK rules for space slots

All online slots in Great Britain, space-themed or not, follow the same rules. Stakes are capped at £5 a spin for players aged 25 and over (from 9 April 2025) and £2 for those aged 18 to 24 (from 21 May 2025), under the Gambling Commission's stake limit guidance (opens in a new tab). Our slot stake limits page has the detail.

Under the game design rules, there's no autoplay, no turbo or slam-stop, a minimum of 2.5 seconds between spins, and no celebrating a return of your stake or less. Since a Gambling Commission warning in January 2020, feature buy-ins are not offered to British players. You'll need to pass age verification before playing, including demo games.

Where to play space slots at UK casinos

None of our three partner offers puts its spins on a space game; they're slot offers on Big Bass Bonanza or selected titles. To find Reactoonz, Rocket Reels or Cygnus, search each casino's lobby. 18+ only, and terms apply.

• PlayOJO: new UK customers, Northern Ireland excluded, get 80 free spins on Big Bass Bonanza with a first deposit of £10 or more. The spins are 10p each and wager-free, so winnings come as cash. No combining with other offers; designated offer link only.
• Coral: new players who deposit and bet at least £10 on slots between 1 October 2026 and 1 February 2027 receive 100 free spins on selected games, each worth 10p. There are 48 hours to accept them and 7 days to use them, with no wagering on winnings. Deposits by Neteller, PayPal, Paysafe, Skrill, prepaid card and certain debit cards don't qualify.
• Ladbrokes: spend £10 or more on slots after depositing as a new customer for 50 free spins a day over 10 days, up to 500. Spins are 10p each on selected games, must be claimed by 23:59 each day, last 7 days and have no wagering. Money paid in by prepaid card, PayPal, Paysafe, Neteller, Skrill or Moneybookers won't count.

Coral and Ladbrokes are run by LC International Limited, so one person may not be able to open new accounts with both. Read the Coral welcome bonus page for the full terms.

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.