(ELK Studios) Slot Review

ELK Studios

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Oxygen: Slot Overview

Big, small, furry, scaled, rich, or poor, there is one thing which almost every person and creature on Earth needs to survive. No, not love, well, maybe that too, but oxygen. However, proving the exception to the rule is at least one animal called Henneguya salminicola, an 8 mm parasite that infects Chinook salmon, which actually does not need oxygen to survive. Such a discovery opens up the possibilities for how animals or beings may have evolved on other planets since what humans thought was crucial for life may instead be a narrow, ignorant definition rather than a wide, abundant understanding of reality. Anyway, back to our home planet now, where the majority of its surface is covered in water, and this watery domain is what plays host to Oxygen, an online slot from ELK Studios.

Oxygen is a cluster paying grid slot played on a 6-reel, 7-row gaming grid floating about at the bottom of the sea. Down here, players are joined by a sunken ship, colourful coral, and a horde of sea creatures on a transparent gaming grid. A bubbling underwater tune adds to Oxygen's tranquil environment; well, it's tranquil in the beginning, at least. ELK Studios has piled on the sort of math and features that can deal tantalising levels of excitement and/or despair, with a very strong hint of Pragmatic Play going. More on this last bit soon.

Oxygen slot
Oxygen slot - base game

Bet levels in Oxygen start from 20 c on the lowest side, rising up to $/€100 at most, and there are five gambling modes available from the X-iter menu. As a cluster pays slot, Oxygen creates a win when at least 5 identical symbols land next to each other in vertical or horizontal directions. Next, the avalanche mechanic removes winning symbols from the reels, allowing others to drop in to fill the gaps, a process that repeats until no new wins are formed. This Oxygen does with a medium/high volatile math model, pushing out an RTP of 94%, no matter how users choose to play the game.

Eight regular pay symbols line the table, made up of 3 low-value buoy-like devices and 4 aquatic creatures as the high pays. Hitting a 5-matching symbol cluster pays 0.1 to 1 times the bet, all the way up to 10-100x the bet for a 14+ sized winning cluster. As well as the normal 1x1 size, pay symbols or wilds may also randomly land in sizes of 2x2, 3x3, or 4x4. Three types of wilds appear in Oxygen, and all are able to substitute for any regular pay symbol. Wins made up of only wilds have the same value as the highest-paying symbol.

Oxygen: Slot Features

Oxygen slot
Oxygen slot - free spins

As well as three wilds, Oxygen has multipliers, multiplier features, a free spins bonus game, a super bonus game, and X-iter feature buy options.


The regular wild simply substitutes for pay symbols, but the other two wilds are able to do special stuff. For instance, the Exploding Wild activates when it is part of a winning cluster. It removes all pay symbols in an X-shape area above and below itself. Exploding Wilds detonate when no more winning combinations appear, and all features within the X-shape are triggered. The third wild is the X-Blaster Wild, triggered when it is part of a win. A random pay symbol or wild symbol is selected and replaces all pay symbols in an X-shape. Exploding Wilds or X-Blasters on its trajectory are triggered. Symbols affected by multiple X-Blasters are turned into wilds.

Multipliers and Multiplier Features

One of Oxygen's most potent features is its multipliers. The first win on a symbol position adds a bubble to it (an x1 multiplier), and each consecutive win on the same position doubles the multiplier up to x2,048. Multiplier values are cleared between paid spins but are persistent between free spins in the bonus rounds. Randomly triggered, the following Multiplier features are also available:

  • The Multiplier Strike feature - places a random number of multipliers on the grid. This feature can trigger on any symbol drop or free drop.
  • The Collector feature - collects all multiplier values in view to its position. The multiplier Collector activates when part of a winning cluster and can be persistent.
  • The Dealer feature – multiplies all multiplier values in an area of one or more adjacent vertically or horizontally V shapes with the value on the Dealer's position (minimum of x2). This feature activates when part of a winning cluster and can be persistent.

Bonus Game

Landing 3 scatter symbols awards 10 free spins in the bonus game. Multipliers are persistent when entering the bonus round and between free spins. Hitting 2 or 3 scatters awards an extra +3 or +5 free spins, respectively.

Super Bonus Game

Landing 3 scatters and a persistent multiplier feature triggers 10 super bonus spins. In the super bonus, multipliers are persistent as in the bonus game, plus at least 1 multiplier feature is persistent as well. Hitting 2 or 3 scatters awards an extra +3 or +5 free spins, respectively.


Opening up the X-iter feature gives players a chance to activate these game modes:

  • Bonus Hunt – 3x the bet where each spin has triple the chance of triggering a bonus.
  • Multiplier Strike – 10x the bet to guarantee the multiplier strike.
  • Persistent Multiplier Feature – 25x the bet to guarantee the persistent multiplier feature.
  • Bonus Game – 100x the bet
  • Super Bonus Game – 500x the bet.
Oxygen slot
Oxygen slot - free spins

Oxygen: Slot Verdict

So, is anyone else getting strong Sugar Rush vibes from this one? Thought so, and the two games have a lot in common. Enough to suppose that ELK Studios liked what they saw in Pragmatic Play's candy slot and decided they'd have a crack. ELK Studios being ELK Studios, though, the team didn't just throw some progressive multipliers at winning grid positions and call it a day. The studio has juiced the core multiplier position mechanic so potential values can be much higher, added in some complementary multiplier features, and tuned the math model to make Oxygen a more do-or-die slot than its sugary predecessor. On the do side, Oxygen has winning potential of up to 25,000x the bet, so its sizable position multipliers aren't just for show, though bigger does not automatically equate to better.

One reason is when having multipliers of over x1,000 in free spins where nothing decides to connect with them, thereby sitting there teasing your eyes by being both valuable and worthless at the same time. On the flipside, hitting even a modest-sized cluster with a massive multiplier might turn out to be pretty sweet or Oxygenic, as it's called in the game. Multiplier features, the Dealer and the Collector, are excellent additions as well, so there are loads of components which can be used to craft a solid hit. The hope, then, is that they darn well link up to do so. Not always so easy to achieve in practice, of course, and even super bonus buys could be hard-pressed to end in credit.

As mentioned, Oxygen is like a more highly strung version of Sugar Rush, with all the bumps, peaks and troughs that equates to. In this well-made game, ELK Studios has taken a popular mechanic and given it a major overhaul so that broadly speaking, compared to Sugar Rush, Oxygen's highs may be higher, the lows may be lower, and the ride, in general, a more turbulent one, for better or for worse.


Oxygen maintains an ok presentation and adds some twists and tweaks, but overall you’re left with an experience that feels very familiar to Sugar Rush.

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