Oxygen 2: Slot Overview

Time to surface for some air with ELK Studios’ slot Oxygen 2, the follow-up to the 2023 underwater title Oxygen. Potentially created as a reaction to the popularity of Pragmatic Play’s Sugar Rush, the original Oxygen delivered a party of per-position reel multipliers that could lock in place and swell to huge levels. Oxygen 2 keeps that signature idea, while tweaking the surrounding elements to serve up a refreshed, fizzy, undersea adventure.

Oxygen 2 sends players back into the depths. A transparent game grid hangs in a shadowy underground grotto filled with coral, pipes, and sand. It looks like the kind of spot where a submarine might have gone down and split apart—hopefully after the crew had time to get out safely. Oxygen 2 isn’t as instantly striking an ocean slot as Razor Returns, for instance, but the reels are packed with colourful creatures that have adapted to the junk humans have dumped into the sea—like a crab sporting a spanner in place of a claw, or a snail making a home in a tin can.

In this sequel, symbols once again fall into a 6-column, 7-row grid, creating winning clusters when 5 or more matching pay symbols connect horizontally or vertically. By clicking the coins button, players can choose a stake from 20 c to $/€100 before enabling X-iter bonus modes, depending on preference. With a 94% RTP, whichever route you take, Oxygen 2 runs on a highly volatile math model

Oxygen 2’s pay symbols include green, orange, and pink floaty icons, alongside 4 higher-paying character symbols. Clusters of 5 OAK pay 0.1 to 1 times the bet, rising to 10 to 100 times the bet for clusters of 16+ OAK. Wilds replace any pay symbol. A full-wild win pays the same as the top-paying symbol. Symbols sized 2×2, 3×3, or 4×4 can appear on any drop. Big symbols may carry multipliers.

Oxygen 2: Slot Features

Play begins with symbols dropping onto the grid, and once winning symbols have paid, they either explode—or, if the symbol is a special wild, it becomes activated to explode later. The empty spaces are then refilled as symbols fall downward, and the avalanche sequence keeps going until no further win lands.

Oxygen Bubbles & Multiplier Strike

The first time a symbol explodes, an oxygen bubble is activated on that position. Whenever a symbol explodes on an oxygen bubble spot, the multiplier value is doubled. A newly activated oxygen bubble starts at x1. Oxygen bubbles stay fixed in place rather than tumbling, and the maximum single value is x2,048. Also, triggering randomly on any spin, the Multiplier Strike feature drops a random number of multipliers onto the grid.

Jellyfish & Octopus Features

One or more Jellyfish may randomly swim in carrying multipliers. Each Jellyfish pauses on a random number of grid positions, adding its multiplier to them. If a Jellyfish stops where a multiplier already exists, the existing multiplier is added to the Jellyfish multiplier and the Jellyfish multiplier is added to the existing multiplier. An Octopus can also randomly appear on the grid, sitting behind 1 symbol position. The Octopus feature activates if a win occurs on that specific position, adding a random selection of the available multipliers outside the winning cluster to the payout, boosting the win multiplier.

Exploding Wild & The Blaster Wild

The Exploding Wild triggers an explode feature when it is part of a winning cluster. This explode effect removes all pay symbols inside two cone-shaped areas pointing left and right, plus up and down from its location. It activates when no more wins appear. Any Exploding Wilds and Blaster Wilds caught within the cones are activated. The Super Exploding Wild activates all unactivated oxygen bubbles behind the symbols that were exploded.

The Blaster Wild triggers when it is part of a winning cluster. The Blaster effect picks a random pay symbol or wild symbol, then explodes and replaces all pay symbols with the chosen symbol in an ‘X’ or a ‘plus’ shaped pattern. Any Exploding Wilds or Blaster Wilds within the pattern are activated. Symbols hit by more than one Blaster Wild pattern turn into wilds.

Free Spins

Landing 3 scatter symbols in the base game awards 10 free spins. All oxygen bubbles and their multipliers persist when entering free spins and between free spins. The Octopus is also persistent during the bonus and moves to a random position at the start of each free spin. Landing 4 scatter symbols in the base game awards the super bonus game. In the super bonus game, the Jellyfish feature triggers before every free spin. Both the bonus game and the super bonus game can be retriggered. Landing 2 or 3 scatters awards +3 or +5 free spins, respectively. If 4 scatters land, the bonus is upgraded to the super bonus +7 free spins are granted.

X-iter

Bonus modes are available through the X-iter menu. Bonus Hunt makes every spin have more than 3 times the chance to trigger the bonus game, and it costs 3x the bet. For 10x per spin, you can buy a spin that guarantees at least 3 special wilds land. Octo Strike costs 25x and guarantees an Octopus plus at least 1 Multiplier Strike on the spin. The bonus can be bought for 100x the bet with an Octopus feature on each free spin, while the super bonus—featuring at least 1 Jellyfish feature and 1 Octopus on each free spin—costs 500x the bet.

Oxygen 2: Slot Verdict

Above all, Oxygen 2 is a polished cluster pays slot. If—and nobody’s accusing anyone—ELK Studios took cues from Sugar Rush when building this game (and the original), they’ve done a strong job recreating the core concept while tying it to lively supporting features. As before, the key objective is to load the grid with oxygen bubbles, then win on top of them to double the relevant individual multipliers—up to x2,048 each. It worked brilliantly in Sugar Rush and in Oxygen, and it can work just as well in Oxygen 2.

That said, it isn’t only about bubbles. Oxygen 2 comes with a bundle of additional mechanics that can kick in. Two standout attractions are the Jellyfish and the Octopus, which can twist the central oxygen bubble multiplier gameplay in unpredictable ways and play a major role in pushing multipliers higher—which is exactly what you’re chasing. When Jellyfish don’t translate into stronger results, though, they can feel a bit irritating. The time they spend drifting across the grid to complete their action is slightly long and can interrupt the pace. Still, they do add suspense, and if their multiplier work pays off—especially with a win cap of 25,000x to aim for—then it’s easy to overlook. Jellyfish aren’t exactly built for speed, even if they do look elegant.

After taking a deep breath and seeing what’s going on down below, Oxygen 2 didn’t feel like a huge leap beyond the first Oxygen, but it does push into slightly different territory. Even if it comes across more like a sideways swim than a giant jump forward, it remains an entertaining cluster-paying slot with plenty of tempting extras.