Cascading reels is a mechanic where, after a win, the winning symbols disappear and the symbols above drop down, with new ones falling in to fill the gaps. If the new arrangement forms another win, it pays and the process repeats, all from the original stake.
What cascading reels are
On a traditional slot the reels spin, stop and the result is final. On a cascading slot the result can change several times within one paid spin. The idea is the same across studios but the names differ: avalanche, tumble, rolling reels and cascades are all versions of it. Some games use falling blocks, others make symbols explode or dissolve, but the maths is the same pattern.
How it works, step by step
- You place a stake and the grid fills.
- Wins are evaluated using the game's pay system, which might be paylines, ways to win, cluster pays or pay anywhere.
- Every symbol involved in a win is removed. The win is added to a running total.
- Remaining symbols fall to fill the gaps, and new symbols drop in from the top.
- Wins are checked again. If there are any, steps 3 and 4 repeat.
- When a refill produces no win, the sequence ends and the total for the spin is paid.
Common variations
- Cascade multipliers: a multiplier that rises with each consecutive cascade, such as ×1, ×2, ×3 and so on, and resets on the next paid spin. In many free spins rounds it does not reset.
- Changing reel heights: on Megaways games each refill can change how many symbols a reel holds.
- Destroying symbols: some features blow up nearby symbols to force a refill, such as Nolimit City's xBomb.
- Meters and progress: removed symbols may fill a meter that unlocks rows or a feature, a kind of grid expansion.
- Different refill sources: some games refill from the same reel strip, others from a separate set, which the designer uses to tune the chances of a chain.
What it does to the maths and the feel
Cascades give a single spin several chances to pay, which tends to raise hit frequency. The designer offsets that with lower values per win, so the overall return stays at the game's RTP. Where cascades are paired with a rising multiplier, a long chain can produce a large result while short chains produce small ones, which widens the spread of outcomes and usually pushes volatility higher.
It is worth knowing that a chain of four or five small cascades can still total less than the stake. The animation can make a losing spin look busy. What matters is the total for the spin compared with what you staked.
Rules in Great Britain
Cascading slots are available on GB-licensed sites. Under the game design rules from 31 October 2021, a game cannot celebrate with sounds or imagery a win that is equal to or less than the stake, and your net position and time played must be shown. Both help with exactly the effect above. The whole cascade sequence is one game cycle, so the stake limits apply to the stake for that cycle, and the 2.5 second minimum applies to the cycle as a whole.
Questions people ask
Are avalanche, tumble and cascade the same thing?
Broadly, yes. They are different studios' names for the same idea: winning symbols are removed and the gaps are refilled within the same paid spin.
Does each cascade cost another stake?
No. All cascades belong to the spin you paid for. They continue until a refill produces no new win.
Do cascades make a slot pay more?
Not in the long run. Cascades are built into the game's maths, so the RTP already accounts for them. They change how wins are spread out, not the house edge.