Das xBoot Slot Overview
Das xBoot is a WW2 submarine-themed slot from Nolimit City, built on a 6-reel grid in a 2-3-4-4-3-2 formation. Inspired by the 1981 German war film Das Boot, the game draws from one of cinema's most claustrophobic settings and translates it into a complex, feature-heavy experience. Starting at 576 ways to win, the layout can expand up to 75,712 under the right conditions.
What stands out here is how many signature Nolimit City mechanics converge in one release. xNudge Wilds, xWays symbols and xBomb Wild Multipliers all appear alongside two entirely separate free spins rounds. Rated 10 out of 10 for volatility by the studio, this is very much a high-risk, high-reward proposition with a 55,200x max win.
Theme, Design and Symbols
Comic book-style visuals define the presentation, with the action set against murky grey seas alongside a German U-boat. Compared to the studio's previous work on Mental, the look here feels slightly less abrasive, though the menacing soundtrack more than compensates. I found the audio particularly effective; a blend of Klaus Doldinger-inspired tension and deep-sea dread that builds genuine atmosphere during longer sessions.
Low-paying symbols are standard 10-A card ranks. Five submarine crew members serve as premiums: a chef, radio operator, engineer, periscope operator and the Kapitanleutnant (captain). The captain pays 20x the stake for six of a kind, while other premiums range from 3.2x to 10x. Special symbols include the xNudge Wild, xBomb Wild, xWays mystery symbol and the Sonar Display scatter on reels 2-5.
The design choice to use retro comic art softens what could be a grim theme, and I think it works. Sinking enemy ships is woven into gameplay rather than just being cosmetic. Still, the WW2 submarine setting will not appeal to everyone, and I suspect some players will find it a bit niche.
Symbol Payouts
| 6 | x20 |
| 5 | x6 |
| 4 | x3 |
| 3 | x0.88 |
| 6 | x10 |
| 5 | x3.2 |
| 4 | x0.6 |
| 3 | x0.4 |
| 6 | x4.8 |
| 5 | x1.6 |
| 4 | x0.52 |
| 3 | x0.32 |
| 6 | x4 |
| 5 | x1.2 |
| 4 | x0.48 |
| 3 | x0.28 |
| 6 | x3.2 |
| 5 | x0.88 |
| 4 | x0.4 |
| 3 | x0.28 |
| 6 | x2.8 |
| 5 | x0.8 |
| 4 | x0.36 |
| 3 | x0.24 |
| 6 | x2.8 |
| 5 | x0.72 |
| 4 | x0.36 |
| 3 | x0.24 |
| 6 | x2 |
| 5 | x0.68 |
| 4 | x0.32 |
| 3 | x0.2 |
| 6 | x2 |
| 5 | x0.6 |
| 4 | x0.28 |
| 3 | x0.2 |
| 6 | x1.4 |
| 5 | x0.52 |
| 4 | x0.24 |
| 3 | x0.2 |
Bonus Features and Free Spins
Several base game mechanics keep things active between bonus triggers. The xNudge Wild is a 4-row stacked wild landing on reels 3 or 4 that always nudges fully into view, adding +1 to its multiplier per nudge. Multiple xNudge multipliers combine additively. xWays symbols appear on reels 2 or 5, revealing 2-3 instances of the same random pay symbol and expanding the ways count. When an xBomb Wild lands, the global win multiplier rises by +1 before it explodes, clearing all non-winning symbols and converting itself into a regular wild.
Landing 3 Sonar Display scatters triggers Silent Hunter Free Spins: 8 spins where reel 3 extends to 8 rows high. A new Periscope Wild can land here, and matching symbols on reels 1-2 with this wild on reel 3 launches a torpedo attack sequence. Sinking the target expands the Periscope Wild across the entire reel while increasing the global multiplier. Each additional scatter adds +2 spins.
Four scatters activate Wolf Pack Free Spins, the top-tier round. A torpedo tube appears beneath reels 2-5. Torpedo wilds drop xWays symbols onto the tube, starting at x2 and climbing to x9 per position. Filling all four slots launches the torpedo, converting positions on reels 2 and 5 into xWays pay symbols and positions on reels 3 and 4 into xWays wilds. Each launch also bumps the win multiplier. The potential here is enormous, but it demands patience; free spins trigger roughly every 211 spins on average.
Bonus Buy Options
RTP, Volatility and Max Win
RTP sits at 96.03% in the highest configuration, though variable RTP means some operators may run a lower 94.02% version. Always check which setting your casino uses before committing real money. Volatility is extreme, rated 10/10 by Nolimit City, with a hit frequency of around 22.07%. Bets range from 0.20 to 100 per spin.
Maximum win potential reaches 55,200x the stake. A Bonus Buy option lets players skip the wait: Silent Hunter Free Spins costs 75x the bet (RTP 96.57%), while Wolf Pack Free Spins costs 350x (RTP 96.58%). Not available in all jurisdictions, notably the UK.
