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All games › The games › Undercog Boilerhall

Undercog Boilerhall

Deep under the decks, giant brass cogs turn, pipes hiss and a cage lift climbs its geared shaft while cyan steam vents into the clouds. Winning parts drop out of the reels, and every further win in the same spin is boosted.

20 linesTumbling reelsHigh volatilityFree account worldCoin RTP 94.5%
Free account

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These games cost nothing and always will. An account holds your 100,000 coins, favourites, level and daily missions between visits — and lets us confirm you are 18 or over before your first spin.

  • 100,000 free coins on signing on
  • No card, no payment page on any deck of the skyport
  • A single balance across each berth you unlock
  • No download — every reel spins in your browser

Play-money coins, nothing more. No real-money gambling, no prizes of real-world value and no in-app purchases. Adults 18+.

We ask for no card and no payment details, and nothing is for sale. Coins hold no real-world value and can never be cashed out.

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About this world

Undercog Boilerhall

Undercog Boilerhall is the hottest berth aboard, the place where the whole skyport gets its lift. Most of its value sits with the Glass Heart and the Shaft Cage, so the engines can idle through a quiet spell before a run of tumbling wins sets every gauge rattling. Each paying line is knocked off the reels, everything above it drops and fresh parts clatter in, the chain rising from single pay to double, triple and finally fivefold. Cyan Gauges never vanish. Three gauges anywhere fire up ten free spins with doubled wins, the chain boost stacking on top; four gauges give fifteen and five give twenty-five.

Cog Drop Chain. Winning symbols vanish and the others drop as new ones fall in; a chain pays its first win at x1, its second at x2, its third at x3 and from then on x5, in paid and free spins alike, with the x2 free-spin multiplier stacked on top.

The honest part

Play money, every time

Every spin aboard uses free virtual coins. No real-money gambling happens here, wins carry no real-world value, and there are no in-app purchases. A random number generator settles each result, and earlier spins never shape the next.

Measured by running this page's own engine for 10,000,000 spins: coin RTP 94.5%, hit frequency 33.9%, free spins about once in 137 spins, a win of 10x your stake or more about once in 81 spins. Coin figures only — no money is staked or returned.

How to play

Undercog Boilerhall in three steps

1

Sign in, step into the cage lift and ride down the geared shaft to the engine hall, then set a stake for the cogs.

2

Spin. Winning parts drop out and new ones clatter down; the opening win of a chain pays its plain value, the next pays double, then triple, then five times for each win beyond.

3

Three Cyan Gauges anywhere fire ten free spins with doubled wins, four gauges fire fifteen and five gauges fire twenty-five.

Who it suits

Patient stokers who will happily sit out a few cold boilers for a shot at a long run of tumbling parts.

What to expect

The widest swings aboard. The Glass Heart and the Shaft Cage hold the heavy pays, so the boilers pay in bursts of steam with cooler spells in between.

Symbol guide

What pays in Undercog Boilerhall

Reel symbol aboardFive on one Vespercombe paylineMeasured against your total stake
Cog Trio (wild)5,000× line bet250× your stake
Shaft Cage2,600× line bet130× your stake
Glass Heart1,400× line bet70× your stake
Ring Gyro800× line bet40× your stake
Red Valve440× line bet22× your stake
Hex Wrench260× line bet13× your stake

The five card ranks (10 to A) pay the least. Three Cyan Gauges anywhere open the free round. Full values for three and four of a kind are in the paytable.

Questions

About Undercog Boilerhall

For as long as every new drop of parts lines up another win. The fourth win in a chain, and each one after it, pays five times.

Yes. Each win in the free round is doubled before the chain boost multiplies it again, and fresh gauges in the round add spins.

That is its nature: the rarer parts carry the larger pays, and the boilers never bank, owe or hold back a win for later.

Today's missions

Four errands for the captain

Missions refresh each day and count in all three worlds. Doing them is entirely up to you.

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18+ onlyFor adults over legal gambling age. Not directed at under-18s.
No real moneyNo real-money gambling is offered or promoted here.
No prizesNothing won has real-world value. Coins cannot be withdrawn.
No purchasesNo in-app purchases. Every coin is free.

Play for pleasure, and leave the deck when the pleasure goes. Pick a time limit before you start and take breaks. If gambling of any kind is causing you problems, the National Gambling Helpline offers free and confidential help on 0808 8020 133, 24 hours a day; GamCare and BeGambleAware can help too. See our responsible play policy.

18+

A free social casino above the clouds, and not one penny of real-money gambling anywhere on board.

Gaslamp Skyport welcomes adults aged 18 or over and nobody younger. Every berth runs on virtual coins of no monetary value, and those coins cannot be bought, sold, withdrawn or exchanged. No coin shop or payment page exists anywhere in the skyport, no prize of real-world value is on offer, and success here does not imply future success at real-money gambling.

No real moneyNo prizesNo in-app purchasesNo withdrawals18+ only

Free, confidential gambling support: National Gambling Helpline 0808 8020 133, 24 hours a day · BeGambleAware · GamCare · The skyport’s responsible play policy