Das xBoot Slot by Nolimit City

The thing to know first is that this game splits into two different bonuses depending on how many Bonus symbols you trigger with. Three Bonus on reels 2-5 routes you into Silent Hunter Spins, eight rounds where reel 3 stretches from four positions to eight and a Periscope Wild appears on that middle column. Four Bonus skips that path entirely and drops you into Wolf Pack Spins, eight rounds on a re-shaped 2-4-5-5-4-2 grid with torpedo tubes installed under reels 2-5. Same trigger, two different feature engines.

The Silent Hunter math leans on a Torpedo Launch sequence. If connecting symbols land on reels 1 and 2 with a Periscope Wild on reel 3, the periscope finds a target and fires a torpedo. A hit grows the Periscope to the top of that 8-row reel, nudges it back down position by position, and adds +1 to a sticky multiplier that locks for the rest of the feature. xBomb explosions during the round also drop sticky +1s. All multipliers add (so x3 plus x4 reads as x7, not x12), and any xBomb multiplier banked on the trigger spin itself carries forward into the bonus.

Wolf Pack is the wilder tier. Torpedo Wilds land on reels 2-5 and drop +1 xWays parts into the torpedo tube under each reel. The first part to land on any tube counts as +2 instead of +1. Once a tube fills, the torpedo launches and the collected xWays symbols are revealed at the size of the tube payload - up to a maximum of 9. Reels 2 and 5 transform those into regular paying symbols split N ways. Reels 3 and 4 transform them into Wilds split N ways. This is how the way-count slingshots from 576 in the base game up to 75,712 at full expansion, and how the 55,200x max cap is meant to be reached.

The base game runs on three boosters simultaneously, which is unusual even by Nolimit standards. xNudge Wilds are 4-row-high stacks that only land on reels 3 and 4 and always nudge into full view, banking +1 to a Wild multiplier per nudge step. xWays Mystery symbols land only on reels 2 and 5, hold 2-3 of the same symbol inside, and if more than one lands they all reveal the same paying icon. xBombs are the cascade engine: they blow up non-winning neighbours, add +1 to the multiplier, and the board collapses to refill. Two feature buys are available - Silent Hunter at the cheaper tier, Wolf Pack at the steeper one.

Visually it's a Das Boot 1981 homage. The reel set sits inside a riveted steel U-boat hull with brass periscope housing overhead, torpedo tube doors at the edges, and dark blue-green ocean depths behind. Crew character symbols are stencil-painted Kriegsmarine officers - Captain, Helmsman, Engine Officer, Radio Operator, Crewman - over military-stencil A K Q J 10 lows. ATTACK and ALARM klaxons flicker over the action. Closer in tone to Tsar Wars than to the studio's horror catalog.