Rainbow King Slot Review

As with many online slots from Novomatic, it builds in familiar gameplay while drawing fully on the theme on which it is based.

Where to play Rainbow King for real money

Basis of this table: the welcome offer each brand publishes for new UK accounts. It is not a list of casinos carrying this game — Lobbies change without notice: check the game is in the operator’s own lobby before you deposit for it.

No wagering6 of 8 shown

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Last updated October 1, 2026 · Every brand listed here holds a current UK Gambling Commission licence; the licence holder and account number are printed on the brand’s own row.

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Fans of the entire Reel King series will be pleased to see the classic playing card symbols make a return and will quickly notice that Rainbow King has a few more features and bonuses up its sleeve to entice a wider range of players to give the reels a spin.

Rainbow King Theme

As the name would suggest, Rainbow King is slightly more colourful than its predecessor. The game’s uppermost title is displayed on a regal purple banner and flanked by crowns and even the background incorporates actual rainbows to brighten up anybody’s day. The reels themselves are packed with opulence, with even the basic playing card symbols being rendered in the style of precious gems. They are joined by an interesting cast of higher value symbols, including the Crown, Sacks of Cash and of course the Rainbow King himself, who looks like a curious cross between Charles I and Humpty Dumpty.

Gameplay and Prizes

Gameplay on Rainbow King offers players the classic mix of simplicity and flexibility when it comes to placing stakes and getting the main gameplay underway. As with the majority of the Reel King series of online slots, players can choose up to twenty win lines, and while the number of coins on each line is fixed, they can adjust the inherent value to suit their tastes. Naturally, our free version of Rainbow King that you can play here at Gamblib includes all of the functionality inherent to the main game.

Players can scoop a 500 coin jackpot on each and every spin. While this may seem somewhat modest in comparison to other jackpots in the slot series, it is more than compensated for through additional bonus features that serve to add to the experience, and of course the profitability.

Features and Bonuses

First up on the list of features that Rainbow King brings to the table is the wild card symbol which, simply enough, is denoted by the word ‘Wild’ on a colourful background that resembles a snowflake. As there are more features and bonuses, plus scatter symbols, the wild card in Rainbow King cannot substitute in for absolutely every symbol on the board, but can nonetheless prove extremely valuable in completing elusive winning combinations.

Next up are three separate bonus rounds, each with a different twist. The simplest of these is the Cash Castle feature, which is activated when the player successfully spins in three or more Castle symbols. Rather than being a separate round in its own right, it gives players the chance to take their pick from three additional Castle icons, each containing a different prize amount based on the player’s stake. As a game of chance it varies in profitability, but players can be assured of at least two times their stake just for activating the feature, rising to an impressive 500 times the original bet on particularly lucky occasions.

Next up is the Rainbow King feature, which will be highly familiar to anyone who has ever enjoyed IGT’s range of Monopoly themed slots – which are incidentally also available here at Gamblib to play for free. Spinning in three or more symbols depicting the curious cross between Charles I and Humpty Dumpty – otherwise known as the Rainbow King – grants access to the round. Players press the Spin button to roll the dice and travel around the board, collecting cash prizes and bonuses as they go. The round even features its own mini bonus games such as free spins. Those spins end when the player fails to spin in a Lucky 7.

Finally, players can enjoy the King Cash feature which reverts to the simpler style of the Cash Castle game. Three Crown symbols on the middle reels activate the feature, where players again choose from different icons to reveal a prize. This feature is harder to access than the Cash Castle game but the rewards are substantially better, with players standing to take down anywhere from fifty to 500 times their stake.

With so many features packed into a single game, slots fans can be entertained by Rainbow King from Novomatic for literally hours on end. What starts off as a simple looking slot quickly becomes much more immersive, something that you can see for yourself by enjoying the game for free here at Gamblib.