Book of Santa Dice Slot by Endorphina

A standard "Book of" engine wearing an unusual costume: every symbol on the reels is a giant 3D dice cube. The low pays are plain red and orange dice with black pips; the premiums are festive dice with a painted face, a golden star, a wrapped gift, a candy cane and Santa's sleigh sliding across a blue cube. It all sits in a gold-edged reel set built into a stone-brick fireplace that glows orange from inside, holly tucked along the top. Cosy Christmas-by-the-hearth dressing on a familiar mechanic.

The Book does double duty. It's the Wild that subs for every regular dice symbol, and it's also the Scatter that pays from anywhere and triggers the feature. Three or more Books award 10 free games, and this is where the "Book of" trick kicks in: at the very start of the round one symbol gets picked at random and handed the power to expand. Whenever enough of that chosen symbol lands, it stretches to fill its full reel and pays for that many of a kind across the enabled lines whether or not they sit next to each other, count is what matters, position isn't. One caveat during the feature: the Book Wild won't substitute for that special expanding symbol, only for the rest. Three more Books inside the round retrigger another ten at the same bet and lines.

The Bonus POP button on the lower left buys those free games directly, and it does something most "Book of" buys don't. Instead of leaving the expanding symbol to chance, a selection step lets you pick which symbol gets the expand power yourself, so you can hand it to a premium rather than hope the random pick lands on one. Price scales with your bet and the option you take. Anything won through Bonus POP is locked out of the card gamble, the standard Endorphina draw where you beat the dealer's face-down card to double a win up to ten times running.

It plays exactly like a classic expanding-symbol book slot, because that's what it is under the dice. The novelty is purely visual, and whether that's enough depends on how much the cube re-skin amuses you, but being able to choose the expanding symbol on a bought round is a genuinely nicer deal than the usual random draw.