Game Design
What are tumbling reels? How cascading wins work
Tumbling reels, also called cascading reels, let a single spin pay more than once. Here's how the mechanic works, with Monaco's 1,024-ways board as the example.
In a classic slot, a spin lands, any wins pay out, and the round is over. Tumbling reels change that last step. The winning symbols are removed, the symbols above them fall into the gaps, new symbols drop in from the top, and the board is checked again. If it pays again, it tumbles again.
The mechanic goes by several names: tumbling, cascading or avalanche reels, depending on the studio. The idea is the same in each case: one paid spin can produce a chain of wins, and the chain keeps going until a board lands with nothing to pay.
Step by step, using Monaco
Monaco’s 5×4 board, before a spin.
Monaco: The Heist uses tumbles on a 5×4 board, so it makes a good worked example.
- Spin. Five reels land, four symbols on each.
- Evaluate. A win is 3 or more matching symbols on adjacent reels, starting from the leftmost reel. Each symbol can sit in any of the four rows. That’s what “ways to win” means: there are no paylines, so with four rows on each of five reels there are 4 × 4 × 4 × 4 × 4 = 1,024 ways for symbols to connect.
- Burst. Every winning symbol bursts and is removed from the board.
- Fall and refill. The symbols left on each reel fall down to fill the gaps, and new symbols drop in from above.
- Check again. The new board is evaluated. If it pays, go back to step 3. If it doesn’t, the chain ends and the spin is over.
Monaco also has a Wild, the Crown Chip, which helps complete ways on reels 2 to 4.
Why designers use tumbles
One spin, several moments. A spin with tumbles isn’t a single result. It unfolds in steps, and each step can extend the chain. That gives a win a beginning, a middle and an end.
Ways and tumbles suit each other. With ways to win, a symbol counts in any row, so the symbols that drop in after a tumble can complete a win anywhere along the reels. On a payline game, new symbols would only help if they landed on the right line.
Readability matters. Because the board changes several times in one spin, each stage has to be easy to follow: which symbols won, what disappeared, and what fell in. Timing, animation and sound all exist to make the chain readable at a glance.
What tumbles don’t change
Tumbles feel generous, but they aren’t free value on top of the game. A game’s return to player (RTP) is calculated over every possible outcome, including every tumble chain. The chains are part of how a game reaches its RTP, not something extra. For more on what that figure does and doesn’t tell you, read how RTP works in slot games.
See it for yourself
Tumbles are easier to understand when you can watch them. The Monaco: The Heist demo is free, uses play money and runs in your browser. The Monaco: The Heist game page has the full rules and specifications.
