The Castle of Slotenstein is the latest in a series of booster-mechanic seasonal slots Evoplay has released throughout 2026, this time built around a Frankenstein theme and a progressive Grand Reel of Fortune finale.
Seasonal-themed slots with layered booster systems have become a recurring release format for European-facing studios in 2026, with Evoplay alone having used the format for its Oktoberfest and Asian-mythology titles earlier in the year. Evoplay released The Castle of Slotenstein on 15 October 2026, a Frankenstein-inspired video slot centred on a three-booster Hold & Win bonus game with a progressive Grand Reel of Fortune finale.
Booster mechanics and the Hold & Win bonus
Seasonal-themed slots with stackable booster systems have become a consistent format for Evoplay throughout 2026, following booster-mechanic releases including 3 Super Volcanoes and Tiger of Fortune. The Castle of Slotenstein applies the same structural template to a Frankenstein theme, set inside a mad scientist’s castle.
Three coloured pumpkin Bonus symbols each trigger a distinct booster when they appear on the reels.
- Green Shock symbols increase the opening number of Bonus Game spins from three to four.
- Purple Trick symbols can generate additional Bonus symbols on their reel or increase the values of existing Bonus symbols by up to 5x.
- Blue Treat symbols add their values to every Orange Bonus symbol already on the grid.
The Bonus Game begins with three or four spins, depending on which boosters are active. Only Bonus symbols appear on the reels during the feature, and every new Bonus symbol resets the spin counter, extending play and giving additional opportunities to fill the grid.
Grand Reel of Fortune and the Bonus Buy
When three Bonus symbols fill a reel, a collect is triggered: their values are added to the win meter and the reel is cleared. The first time each reel is completed, one of five sections of the Grand Reel of Fortune is unlocked. Unlocking all five sections triggers a final spin on the Grand Reel of Fortune, which awards one of eight possible outcomes — multipliers of 2x, 3x, 5x and 8x, or one of four fixed prize tiers: Mini, Mega, Super and Grand.
Players can also access the Bonus Game directly through a Bonus Buy option, with the choice to enter with one, two or all three boosters already active.
Ivan Kravchuk, CEO at Evoplay, said:
‘The Castle of Slotenstein gives the classic Frankenstein story an Evoplay twist, combining a spooky Halloween setting with a feature set designed to keep the action building. The three boosters each change the way the Bonus Game develops, while the Grand Reel of Fortune gives players a target to chase as they work through the feature.’
About Evoplay
Evoplay is an iGaming content developer founded in 2017, with a catalogue of more than 250 slots, table, crash, and instant-win games distributed to operators across more than 100 countries. The studio holds a B2B Critical Gaming Supply licence from the Malta Gaming Authority and has additional certification from Ontario’s AGCO and Swiss authorities. Its European distribution footprint includes Austria, Spain, Malta, and the Czech Republic.
