Oxygen 2 Slot Review

ELK went back underwater, and the idea holding this one together is small and stubborn: blow up the same square twice and it starts paying you extra. Oxygen 2 is a cluster pays game on a six-column, seven-row grid, set in a flooded industrial wreck. Every symbol that explodes leaves an oxygen bubble stuck to its position, and every later explosion on that spot doubles the bubble's multiplier.

Everything else exists to force explosions where those bubbles already sit. Exploding Wilds clear cone-shaped chunks of the grid, Blaster Wilds redraw an X or a plus of symbols, a jellyfish drifts in carrying multiplier values, and an octopus hides behind a random position waiting for a win to land on it. The 25,000x ceiling comes from stacking all of that in one round, not from the symbols themselves. Sixteen matching premiums pay 100x and no more.

RTP is 94%, and drops connect roughly 29% of the time. Neither figure is doing the player any favours.

The setting is a drowned industrial site. Steel pipework and valve wheels rust under deep navy water, chains disappear into the murk, and spiked naval mines hang in the background like someone decorated the place badly on purpose. Pink and purple coral crowds the lower corners. The reels sit on a faint translucent panel over the whole thing, which stops the busy artwork from swallowing the symbols, and it works.

The symbol set splits sharply. Low pays are glossy buoys with little loops on top, in green, orange and pink, and they look like bath toys. The premiums have far more character: a green snail hunched inside a battered tin can, an orange crab gripping a spanner and grinning with a full set of teeth, a fat pink fish with rubber lips, and a red octopus in a brass diving helmet peering through the porthole. Wilds are the mines, gold W stamped on the casing. Bonus is a treasure chest spilling coins. The soundtrack is upbeat and a little generic. And the jellyfish animation runs long enough that you notice it the fourth time, then resent it the tenth.

Base game is thin. Bubbles wipe clean at the end of every round, so all that patient doubling gets thrown away the moment the drops stop, and with wins landing on under a third of rounds you spend a lot of time watching buoys fall into nothing. It plays like a game that is waiting for permission to start.

The bonus is where the design finally makes sense. Once bubbles persist, the grid slowly turns into a scoreboard, and the tension shifts from whether you win to whether the wins land on the right squares. Watching a x64 sit in the corner while clusters keep forming on the wrong side of the board is a specific kind of frustration ELK has clearly designed on purpose.

Pace is the weak point. The jellyfish takes its time crossing the reels and does it whether or not the trip is worth anything, which on a long session adds up to a lot of dead seconds. For my money the 25x Octo Strike buy is the honest way to play this one, because it delivers the actual hook in a single drop instead of asking you to grind base spins for it.

The bubble grid is a good mechanic and Oxygen 2 knows it, building four wild types and two random helpers around the single job of exploding the same squares repeatedly. The Octopus in particular does something most cluster slots don't, sweeping up multipliers that never touched the winning cluster. When a bonus runs long enough for the board to fill with grown bubbles, this is one of the more interesting underwater slots ELK has made.

The cost is patience. A 94% return with wins on under a third of drops is a hard combination, and the base game gives back everything it builds at the end of each round, which drains the tension out of the part you spend the most time in. The sequel additions are worth having (the original's multiplier setup was flatter) though nobody should expect the jump from Oxygen to Oxygen 2 to feel like a new game. It plays like the same idea with better plumbing.