Oxygen 3

Elk Studios sets Oxygen 3, the third game in the series, inside Coral Creek, a flooded, half-ruined city where a submerged monorail and the remains of an advanced civilisation sit beneath the waves alongside the game's aquatic cast. Oxygen 3 keeps the six-reel, seven-row cluster grid the series is built on, but gives it a darker, more atmospheric backdrop than its two predecessors.

A win needs five or more matching symbols connected horizontally or vertically anywhere on the grid; winning positions clear and new icons drop from above to refill them, with the avalanche repeating for as long as further clusters keep forming. The biggest clusters, 32 symbols or more, pay 20x to 250x the stake, and pay symbols can also land oversized in 2x2, 3x3 or 4x4 blocks that count toward the cluster as multiple regular-sized icons. Volatility is rated 7 out of 10, hit frequency runs at 33%, and the game returns to a 96% RTP setting, alongside 94% and 92% alternates, across the full 0.20-100 stake range.

The paytable holds three coral pieces as the lower pays, three fish types, and an octopus as the single top-paying icon.

Every symbol explosion on an empty grid square creates an Oxygen Bubble worth x1; each subsequent explosion on that same square doubles its value, and the bubbles hold their position rather than dropping with the rest of the reel. A separate Multiplier Strike event can seed clusters of these bubbles onto the grid before a drop even begins.

The Clam symbol doubles as a wild, and landing one inside a winning combination triggers one of three follow-on effects. A Squid leaves a wild on its current square and keeps moving to new positions until it exits the grid entirely. A Pearl marks one payout symbol type as sticky across the board and keeps refilling the grid until no further matches of that symbol or wilds appear, then releases the sticky icons into a final win, with only one Pearl effect running at a time. A Starfish faces a random direction, horizontal, vertical or diagonal, clearing pay symbols along that line and boosting a multiplier where it stops, repeating until it eventually becomes a wild itself.

Two further wild types chain off each other. The Blaster Wild activates when it is part of a win, or when struck by another Blaster Wild, an Exploding Wild or a Starfish, converting every pay symbol inside an X or plus-shaped pattern into one matching type; a symbol hit by two separate blasts becomes a wild. The Exploding Wild activates on the same triggers and instead clears pay symbols within two cone-shaped zones running either up and down or left and right from its position.

Three bonus scatters award ten free drops, with two or three scatters worth an extra three or five drops. An Oxygen Meter fills with every winning combination during the round; reaching full boosts a cluster of grid multipliers before the meter empties and starts refilling, and any Oxygen Bubbles already in play carry across between drops. If one of the triggering scatters is a super scatter, the round upgrades to the Super Bonus Game instead, where a larger Super Oxygen Meter works the same way toward a bigger multiplier boost, with meter progress in both versions carrying over between drops.

The X-iter feature-buy menu runs to four options: Bonus Hunt for 2.5x the stake or Mega Hunt for 5x, each raising the odds of triggering a bonus round on the purchased spin; Clam Chowder for 25x guarantees three Clam symbols land on the grid; and the bonus round itself can be bought outright for 100x, or the Super Bonus Game for 250x.

Maximum win potential runs to 25,000 times the stake, and between the Oxygen Bubbles, the Clam modifiers and the wild chain reactions, Oxygen 3 tends to build value gradually across a session rather than deliver instant, one-spin swings.