Oxygen 2

Elk Studios built Oxygen 2 as a follow-up to its 2023 title Oxygen, moving players back into the same drowned wreck of pipes, coral and sand but rebuilding the feature set almost from scratch. Oxygen 2 keeps the six-reel, seven-row cluster grid of the original and adds a fresh cast of sea life working alongside the multiplier system that made the first game distinctive.

The grid holds six columns and seven rows, with wins forming wherever five or more identical symbols touch horizontally or vertically. Winning icons clear from the board and the remaining symbols fall to fill the gaps, and that avalanche keeps running until no further cluster appears. A five-symbol cluster returns 0.1x to 1x the stake, climbing to a 10x-100x payout once a cluster reaches sixteen or more matching icons; pay symbols and wilds can also land in 2x2, 3x3 or 4x4 blocks, and the larger versions can carry their own multiplier.

Low-value pay symbols come as three colours of floating debris, backed by four higher-paying character icons. A single wild type substitutes for any pay symbol, with an all-wild cluster valued the same as the top-paying character.

Every position that produces its first symbol explosion gains an Oxygen Bubble multiplier, starting at x1; each further explosion on that same square doubles the value, up to a cap of x2,048, and the bubbles stay put rather than falling with the tumbling reels. The Multiplier Strike can also fire on any spin, scattering a random spread of extra multiplier bubbles across the grid.

Jellyfish and Octopus creatures extend the multiplier system further. A Jellyfish drifts across a random number of grid squares carrying its own multiplier, stacking with anything already sitting on the positions it passes through, while an Octopus hides behind a single square and pulls a random selection of the grid's other multipliers into any win that lands there.

Two special wilds handle detonations. The Exploding Wild clears pay symbols inside a pair of cone-shaped zones running left-right and up-down from its own position once no further wins remain, lighting up any inactive Oxygen Bubbles caught in the blast as a stronger Super Exploding Wild. The Blaster Wild instead picks one random pay symbol and swaps every matching icon inside an X or plus pattern for it; a symbol struck by two separate blasts turns into a wild outright.

Landing three scatters awards ten free spins, with two or three scatters on the same drop worth an extra three or five spins. Oxygen Bubbles carry their multiplier values into the round and between spins, and a persistent Octopus relocates to a new square at the start of each free spin. A fourth scatter unlocks the Super Bonus Game instead, guaranteeing the Jellyfish feature before every spin and adding seven spins on top; both bonus rounds can retrigger.

A five-option X-iter menu covers Bonus Hunt for 3x the stake, tripling the normal chance of triggering a round; a 10x purchase guaranteeing at least three special wilds on the next spin; Octo Strike at 25x guaranteeing an Octopus plus a Multiplier Strike; the bonus round bought outright for 100x with an Octopus on every free spin; and the Super Bonus Game for 500x with both a Jellyfish and an Octopus guaranteed each spin.

Oxygen 2 runs at high volatility rather than the medium/high setting of its predecessor, with the RTP held at 94% and a maximum win of 25,000 times the stake. Stakes span 0.20 to 100 per spin, and with three separate multiplier systems layered on top of each other, the game leans toward long, quiet stretches punctuated by clusters that can escalate fast once a few Oxygen Bubbles start stacking.