Built by the Lodge · Live on Stake
Slime Lab
An axolotl scientist's lab where a shattered Catalyst Vial fuses matching goo into the next creature up — and every fusion fills a tube that vents giant MEGA GOO wilds.
- RTP
- 96.50%
- Max win
- 10,000×
- Volatility
- High
- Grid
- 6×5
- Paylines
- 15,625 ways
Stake.us is a free-to-play sweepstakes casino — no purchase necessary, and it's blocked in a number of US states. Our signup walkthrough covers which.
Outside the US, the same game is on Stake.com. Stake.com doesn't serve the US and isn't available in every country either, so check it's allowed where you live. That link carries no referral code.
Heads up: we built this one, so we're biased. We earn when you play it, and our Stake.us link carries our referral code. Play it for fun, set a budget first, and stop while it's still fun. Full disclosure.
See it play
The idea
Most tumble games clear a win and drop new symbols in. Slime Lab does that too — a 6×5 board, 15,625 ways, and every win tumbles for another — but it adds a second way for the board to change: fusion. The lab belongs to Dr. Fizz, an axolotl scientist who stands beside the reels, and the symbols are his experiments: lab glassware at the bottom of the paytable, goo creatures above it.
The Fusion
When a Catalyst Vial lands, it takes the largest group of matching goo touching it — a chain of one symbol, joined side by side — and fuses it into the next symbol up the ladder. Only one member of the group has to touch the Vial, and the cell that transforms is the one nearest the group's own centre, so it can sit a step away from the Vial. Fused slimes can fuse again.
The ladder runs from the glassware up through the goo creatures, from Minty near the bottom of the creatures to Sunny at the top. In the main game it stops at Sunny. In free spins it goes one rung further: a Sunny group fuses straight into MEGA GOO wilds.
The Specimen Tube
Every fusion adds to the Specimen Tube beside the reels. It's a counter, not a multiplier — nothing in this game multiplies a win except the ways count itself. In standard play the tube marks at 3, 6 and 9 fusions, and each mark vents MEGA GOO wilds onto the board, which stay for the rest of the tumble. MEGA GOO is never on a reel strip: the tube and, in free spins, a Sunny fusion are the only ways it gets onto the board. In the main game the tube resets every spin.
Free spins
Three, four or five Reactor Cores on the opening reveal award 8, 10 or 12 free spins; cores that tumble in later don't count. Retriggers add +2, +3 or +4, up to 14 spins in total. In free spins the tube holds across the whole round instead of resetting, and the ladder reaches MEGA GOO. The two 100× modes go straight in on different profiles: Meltdown brings frequent Vials and climbs one rung per fusion; Overreaction brings rarer Vials but climbs two rungs at a time.
Same stake, different reaction
Standard Play and Cold Fusion both cost 1× and both return 96.50%: two shapes of the same game, picked before you spin. Cold Fusion runs on its own reels — Vials reach far more boards, the tube marks at 2, 4 and 6 and releases one MEGA GOO wild per mark, and tumbles stop after four steps. Many small returns rather than a few large ones. Vial Boost adds Vials for a single spin at 1.5×. Pure Culture, at 50×, is one spin on reels with the glassware stripped out entirely, so every fusion visibly makes a bigger creature and each tube mark floods two MEGA GOO wilds. It's a spin, not a free-spins entry.
Why we built it
Slime Lab is a mad-science merge game. A Catalyst Vial fuses touching goo into the next creature up the chain, every fusion fills the Specimen Tube, and when it's full it vents giant MEGA GOO wilds across the board. We wanted every tumble to feel like an experiment that might go very right.
Every way to play it
Pick your ride: play it from the base game, or jump straight to the good part. Every mode runs the same 96.50% RTP, so it's purely about how you like to play.
| Mode | Cost | RTP | What it does |
|---|---|---|---|
| Standard Play | 1× | 96.50% | Ways, tumbles and Catalyst Vial fusions; the Specimen Tube marks at 3, 6 and 9 fusions |
| Cold Fusion | 1× | 96.50% | The same 1× stake on its own reels: Vials reach far more boards, the tube marks at 2, 4 and 6 with one MEGA GOO wild per mark, and tumbles stop after 4 steps. Many small returns |
| Vial Boost | 1.5× | 96.50% | More Catalyst Vials, so more fusions, for that spin only |
| Pure Culture | 50× | 96.50% | One spin on special reels with no glassware: every fusion makes a bigger goo creature, each tube mark floods 2 MEGA GOO wilds, and tumbles stop after 4 steps. Not a Free Spins entry |
| Meltdown | 100× | 96.50% | Straight into Free Spins on the steady profile: frequent Vials, and every fusion climbs one rung |
| Overreaction | 100× | 96.50% | Straight into Free Spins on the spiky profile: rarer Vials, but every fusion climbs two rungs |
Where to play it
Slime Lab is live on Stake.us in the US and on Stake.com outside it, exclusive to Stake, and built on Stake Engine — Stake's platform for independent studios.
New to Stake? Our signup guide takes two minutes and covers which states Stake.us is open in. Stake.com isn't available in every country, so check it's allowed where you live.
Questions people actually ask
What is the Slime Lab RTP?
96.50% in every one of its six modes, and the table above lists each. Cold Fusion and Pure Culture change the shape of a spin.
What is the max win on Slime Lab?
10,000× your bet, the same cap in every mode.
Is the Specimen Tube a multiplier?
No. It counts fusions, and each mark vents MEGA GOO wilds onto the board. The only multiplication in Slime Lab is the ways count: the number of matching symbols on each reel of a win, multiplied together.
How does a Catalyst Vial decide what fuses?
It takes the largest group of one matching symbol touching it, joined side by side, and fuses it up the ladder — one rung, or two on the Overreaction profile. Only one member of the group has to touch the Vial, and the cell that transforms is the one nearest the group's centre, so it can sit diagonally away from the Vial.
Does Pure Culture give free spins?
No. It's a single spin at 50× on special reels with the glassware removed. Free spins still start from three or more Reactor Cores, exactly as in standard play.