Double Stacks

Double Stacks Slot Review

NetEnt built their reputation on creating polished, accessible slots that balance visual appeal with solid mechanics–and Double Stacks represents that philosophy perfectly. Released in September 2018, this game doesn’t chase trends or overcomplicate things. Instead, it refines the classic fruit machine aesthetic with a vibrant 80’s neon theme, crisp graphics, and a core mechanic built around stacked symbols and doubling wins. Those who love a nostalgic game that’s easy to play will find plenty to appreciate here, whilst players seeking complex bonus structures may find it straightforward.

Base Game & Features

Double Stacks operates on a traditional 5×3 reel configuration with 10 fixed paylines. The betting range spans from 0.10 to 100 per spin, making it suitable for both cautious players and high rollers. The game uses classic fruit machine symbols–bells, bars, lucky sevens, and diamonds–rendered in bright, bold graphics that pop against the neon-lit backdrop.

What sets Double Stacks apart is its namesake mechanic. When a reel stops with only one type of symbol filling all three positions, those symbols are doubled in the win calculation–counting as two instead of one. This means landing a full stack of matching symbols doesn’t just give you a winning line, it effectively multiplies your payout. The four highest-paying symbols (bell, bar, red seven, and diamonds) can appear as stacked reels, significantly boosting your chances of triggering this feature.

The wild symbol substitutes for all paying symbols except scatters, helping complete winning combinations across the paylines. In the base game, wilds appear regularly but become even more valuable during the bonus round.

Symbol Payouts

The paytable structure is straightforward, with maximum payouts achieved when landing 10 matching symbols (via the doubling mechanic):

• Diamonds: 1000x for 10 symbols
• Red Seven: 500x for 10 symbols
• Bar: 250x for 10 symbols
• Bell: 100x for 10 symbols

Whilst these payouts are respectable, some players have noted that compared to higher-variance titles like Book of Dead (which offers a 5000x max win), the 1000x maximum win potential feels modest. However, the medium volatility means wins arrive with reasonable frequency, creating a balanced risk-reward profile.

Double Stacks Free Spins

Free spins are triggered by landing scatter symbols anywhere on the reels, with the number of spins awarded scaling based on scatter count:

• 3 scatters: 5 free spins
• 4 scatters: 15 free spins
• 5 scatters: 30 free spins

During the bonus round, the game’s potential truly opens up. Wild symbols can appear stacked on the reels, and all four of the highest-paying symbols remain stacked throughout the feature. This creates significantly more opportunities for the Double Stacks mechanic to trigger, and when it does, the results can be substantial.

The feature can be retriggered by landing additional scatters during free spins. The retrigger structure mirrors the initial trigger:

• 2 scatters: +2 free spins
• 3 scatters: +5 free spins
• 4 scatters: +15 free spins
• 5 scatters: +30 free spins

Whilst some reviewers noted that “fans of feature-laden games will be rather disappointed, as a simple free spins round won’t satiate their hunger for head-turning random features,” others found the straightforward approach refreshing. The focus remains squarely on stacked symbols and the doubling mechanic rather than introducing entirely new systems during the bonus.

Our Honest Verdict

Rating: 7.5/10

Double Stacks occupies an interesting position in NetEnt’s portfolio. It’s not trying to reinvent the wheel–it’s a straightforward, well-executed slot that appeals primarily to players who value clarity, visual polish, and nostalgia over mechanical complexity. The 96.1% RTP sits comfortably in the average range, and the medium volatility creates a balanced pace that neither drains your bankroll too quickly nor makes you wait forever for a decent hit.

The game’s strongest selling points are its visual design and audio quality–multiple reviewers praised the “fantastic visuals” and “smooth playability” across both desktop and mobile. The mobile optimisation is particularly solid, with responsive controls and crisp graphics that work seamlessly on smaller screens. For new players or those who appreciate the retro aesthetic, Double Stacks delivers an accessible, enjoyable experience.

However, this simplicity comes at a cost. As one reviewer put it, this is “a solid attempt just not very imaginative.” The 1000x max win is respectable but unexciting when compared to competitors offering significantly higher potential. Some players also found the volatility classification unclear–whilst officially listed as medium, actual gameplay experiences varied, with some noting the game “goes through your funds very quickly with only rare payoffs.”

Who should play this? Classic slot enthusiasts, casual players seeking simplicity, and mobile gamers will find Double Stacks delivers exactly what it promises. If you’re chasing massive progressive wins or complex multi-stage bonuses, you’ll likely find it underwhelming. But for a polished, straightforward slot with decent win frequency and excellent presentation, it’s a solid choice that won’t leave you bored–even if it won’t feature on many “favourite slots” lists.

Frequently Asked Questions

• What is the RTP of Double Stacks slot?

  The RTP (Return to Player) of Double Stacks is 96.1%, which is considered average amongst slot games and falls within the typical 95–96.49% RTP range. This means that over the long term, the game returns 96.1% of all wagers to players, with the remaining 3.9% representing the house edge.
• What is the maximum win in Double Stacks slot?

  The maximum win in Double Stacks slot is 1,000x your stake on a single spin. This is achieved through landing matching symbols across the paylines, particularly when the Double Stacks feature triggers and symbols count as two instead of one. Whilst this max win is modest compared to some high-volatility competitors, it aligns well with the game’s medium volatility classification.
• How many paylines does Double Stacks have?

  Double Stacks is played on 10 fixed paylines across 5 reels and 3 rows. You need to land at least three matching symbols from left to right on a payline to form a winning combination. The fixed payline structure keeps the gameplay straightforward and easy to understand, particularly for players new to online slots.
• What are the Double Stacks feature and how does it work?

  The Double Stacks feature is the core mechanic of the game. When a reel stops and contains only a single type of symbol (filling all three positions), every symbol on that reel is doubled in the win calculation–symbols count as two instead of one when wins are calculated. This can significantly boost your chances of landing substantial wins, particularly when multiple reels trigger the feature simultaneously or when high-value symbols like diamonds or sevens stack up.
• How do you trigger free spins in Double Stacks?

  Free spins are triggered by landing scatter symbols anywhere on the reels. Three scatters grant you 5 free spins, four scatters award 15 free spins, and landing five scatters unlocks the maximum 30 free spins. You can also retrigger free spins by landing two or more scatters during the bonus round, with the same scaling structure applying to additional spins awarded.
• Is Double Stacks volatile?

  Double Stacks is classified as a medium volatility slot, meaning it offers a balance between win frequency and win size. The game pays out prizes fairly regularly but with moderate values, making it suitable for players who prefer steady gameplay without extreme variance. This contrasts with high-volatility slots that offer less frequent but potentially larger wins, or low-volatility slots with very frequent but smaller payouts.
• What symbols and features are in Double Stacks?

  Double Stacks features classic fruit machine symbols with the four highest-paying symbols (bell, bar, red seven, and diamonds) appearing as stacked reels. The game includes wild symbols that substitute for other paying symbols and can appear stacked during free spins for enhanced win potential. The core Double Stacks feature doubles symbol counts when an entire reel contains only one symbol type, creating opportunities for significantly boosted payouts.
• Can you play Double Stacks on mobile?

  Yes, Double Stacks is fully optimised for mobile and tablet play. The game is available on both iOS and Android devices and works seamlessly across desktop, mobile, and tablet platforms. The responsive interface, crisp visuals, and intuitive controls ensure a smooth experience regardless of screen size, making it an excellent choice for players who prefer gaming on the go.