The Castle of Slotenstein

The Castle of Slotenstein is a Frankenstein-themed Halloween slot from Evoplay, released on 15 October 2026 after an exclusive window earlier in the month. The subtitle on the logo reads “3 Pumpkins”, and that is the heart of the game: three glowing pumpkins above the reels power a Hold and Win bonus. The slot has 5 reels and 3 rows with 20 paylines, the RTP is 96.2%, the volatility is medium and the game promises wins of more than 3,000x the bet.

A Haunted Hilltop

Behind the reels, a lonely castle with a lit window stands on a hill under a dark blue sky, with a crooked tree on one side and a gravestone with candles on the other. The three pumpkins on top of the grid are called Shock in green, Trick in purple and Treat in blue, and they glow brighter when they take part in a bonus. The low symbols are the card ranks J, Q, K and A, while the premium ones are laboratory items: green potion syringes, a skull book and a brain in a jar. A Bonus Buy pumpkin sits on the left, and four jackpot plaques are lined up beside the reels.

Controls And Menu

The demo starts with a balance of 5,000 and a default bet of 10, and the bet can be changed with the minus and plus buttons at the bottom of the screen. The central green button spins the reels, and the smaller buttons beside it hold further spin options. A menu on the left opens the paytable, the rules, the settings and the Bonus Buy window, together with a full screen switch, so all the details are only a click away. The rules page is worth a look before you play, because the three boosters and the Grand Reel of Fortune have more details than the short intro screen shows.

Base Game And Bonus Symbols

The base game is a simple line slot, and the card symbols and the lab items pay from left to right. A Wild can appear on reels 2 to 5. Any pumpkin Bonus symbol can start the Bonus Game with one, two or three boosters, depending on the colors that land: a green one switches on Shock, a purple one Trick and a blue one Treat. Everything important happens in this bonus, because the game has no separate round of spins.

The Three Boosters

Each booster changes the Bonus Game in its own way:

• Shock (green) raises the number of Bonus Game spins from 3 to 4;
• Trick (purple) fills empty positions on its reel with Bonus symbols and raises the value of the orange ones on the same reel;
• Treat (blue) adds its own value to every orange Bonus symbol on the grid.

When all three are active, the round starts with the maximum number of spins, a head start in filled positions and bigger values on the screen.

Hold and Win Respins

The Bonus Game works like a classic Hold and Spin round, where only Bonus symbols can land on the reels. Every new symbol resets the spin counter, so a lucky streak can keep the round alive for a long time. When three Bonus symbols fill one reel, their values are added to the win meter and the reel clears, which creates space for new symbols. In the demo, the symbols showed values like 1.0, 1.5, 2.0 and 5.0 in the corners of the pumpkins, and a blue pumpkin with a larger value of 5.0 or 50 could change the result of the whole round.

The Grand Reel Of Fortune

Above the reels, a strip of chained locks shows the progress of the Grand Reel of Fortune. Completing reels unlocks the five sections one by one. When all five are open, the game gives one final spin on the Grand Reel, which pays one of eight prizes: 2x, 3x, 5x or 8x multipliers, or the Mini, Mega, Super or Grand jackpot. At a bet of 10, the jackpot plaques showed 500, 1,500, 5,000 and 30,000, which equal 50x, 150x, 500x and 3,000x the bet.

Our Bonus Buy Session

We used the Bonus Buy at a bet of 10. The menu offers two packages: the Up to 3 Boosters package for 480 (48x) and the All 3 Boosters package for 960 (96x). We took all three boosters, confirmed the purchase and saw the intro screen explaining Shock, Trick and Treat. The round began with 4 bonus spins, and the reels slowly filled with orange pumpkins, with blue and purple ones among them. After a few spins, the lock strip above the grid began to open, and the bonus counter went back up to 4 every time a new pumpkin appeared.

Bet Range And Buy Options

Bets run from 0.10 to 200 per spin. The two Bonus Buy packages cost 48x and 96x the bet, and the first one lets the game choose between one and three boosters at random. Because the bonus has no fixed spin count beyond the 3 or 4 starting spins, the cost of a bought round can return much more or much less than the price, and the result depends on how many pumpkins the respins bring.

RTP, Volatility And Max Win

The RTP is 96.2%, and the volatility is medium, although some previews describe the game as lower than that. The maximum win is 3,000x the bet, which matches the “win over 3000x” promise on the start screen and the Grand prize of 30,000 at a bet of 10.

A Seasonal Pick For Bonus Fans

The Castle of Slotenstein is made for players who enjoy the Hold and Win format with extra layers. The three boosters give the bonus a lot of variety, the Grand Reel of Fortune adds a clear goal, and the Halloween setting makes it a nice choice for the season. The bonus-focused design keeps the rounds simple and fast, and there is no second feature round to learn.

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