PopWins Slots and Win-Driven Reel Expansion Explained
In most slots the grid is the same size however well a spin goes. In a win-driven expansion game, the win itself makes the grid bigger before the next check. HelioPOPolis is the easiest one to picture: each winning symbol pops and is replaced by two, so its reel gets taller, and if the bigger layout wins again, it keeps growing.
AvatarUX calls its version PopWins. Other studios get the same effect differently, adding whole rows or extra reels, so PopWins is one way of doing it rather than the name for all of them.
What is win-driven reel expansion?
A win happens, the game adds playable positions and the larger layout is checked again. The extra space might be taller reels, another row or an extra reel on the side.
How it fits with Expanding Reels
It’s one branch of Expanding Reels. Other games grow their grid when a bonus starts, a random event fires or a symbol is collected. Here, the win itself has to cause each growth step.
What is PopWins?
PopWins is AvatarUX’s name for its own version, not a general name for every expanding grid. Its best-known game is HelioPOPolis. I remember that one coming through mainly because of the name, which is a bit unusual.
How does PopWins work?
In HelioPOPolis, it runs as a simple loop:
- a winning combination forms;
- the winning symbols pop;
- each winning symbol is replaced by two symbols;
- the affected reels become taller;
- the game evaluates the larger layout again;
- another win can continue the sequence.
It looks a little like a cascade, but the replacement doesn’t just refill the same spaces. Because each winning symbol becomes two, the reel itself gets taller.
How tall can PopWins reels become?
HelioPOPolis has specific limits: six symbols tall in the base game and eight during Free Spins. Those are HelioPOPolis rules, not limits shared by every game that expands after a win.
What happens when the expanded state ends?
In the HelioPOPolis base game, the grown reels reset when the PopWins sequence ends. Free Spins are different: the reels reset to the height of the shortest current reel, so some of the growth can survive into the next spin.
Other games draw the line elsewhere. Dragon’s Fire Infinireels removes its extra reels as soon as one fails to improve the win, as explained below.
Whole-row expansion beyond PopWins
PopWins isn’t the only way a win can make the play area larger. These three games add a whole row at a time during a continuing win sequence. All three are from ELK Studios, which uses growing grids in several of its games.
| Game | Growth rule | What it shows |
|---|---|---|
 Cygnus 2 |
Each consecutive Avalanche win adds a row at the top, from 4 rows up to 8. | Whole rows grow, rather than single reels as in PopWins. |
 Katmandu Gold |
Winning symbols explode, replacements drop in and an additional row is added at the top during continuing Avalanches, up to 8 rows in the ordinary sequence. | A cascade and win-driven growth working together. |
 Nitropolis 5 |
Each continuing win adds a row at the top, up to 8 rows. | In Free Spins, each winning spin raises the Safety Level by one row, so later spins start taller. |
Horizontal expansion and InfiniReels
Dragon’s Fire Infinireels grows sideways instead. A win locks the existing reels and adds another to the right. If that reel improves the win, it locks too and the game can add another. If it doesn’t, the added reels are removed and the extension stops.
Red Tiger’s own documents give different starting sizes, so I’ve left the number out.
Win-Driven Reel Expansion vs Cascading Reels
Both can carry on after a win, but a cascade can replace symbols in the same number of positions. Win-driven expansion makes more positions playable. Katmandu Gold does both: winning symbols disappear, new ones fall in, and the next Avalanche adds a row at the top.
Put simply, the cascade explains the symbol replacement. Win-driven expansion explains why the play area itself gets bigger.
Does win-driven expansion always increase Ways?
Not necessarily. Ways to Win is a separate payout system, although a taller grid can mean more possible combinations in a Ways game.
Cygnus 2 grows from four rows and 4,096 Ways to a published ceiling of eight rows and 262,144 Ways. HelioPOPolis is less tidy. AvatarUX gives a maximum of 32,768 Win Ways, though some of its own material shows different counts, so I’ve stuck with the stated maximum.
PopWins and increasing multipliers
Growing reels and growing multipliers are separate rules. In HelioPOPolis Free Spins, AvatarUX documents a +1 multiplier increase for consecutive wins. Its wording on an additional modifier tied to full reel unlocks isn’t consistent, so I haven’t given an extra value.
The Increasing Multipliers guide explains how multiplier progression works in other games.
PopWins and Win-Driven Reel Expansion FAQ
Is PopWins the same as Cascading Reels?
No. A cascade can replace symbols while keeping the same number of positions. In PopWins, each winning symbol is replaced by two, so the reel itself gets taller.
Do more Ways mean a better chance of winning?
No. A bigger grid can mean more ways, but that doesn’t tell you the RTP or how often the game pays.
Sources reviewed
I checked these games against developer documents, in-game rules and game sheets. Some evidence is only available in-game or through authenticated sources; the public links identify the games.
AvatarUX
ELK Studios
Red Tiger
Where this guide comes from
I check the games’ own rules and developer material, and where the sources disagree, I keep the disagreement visible rather than picking a number. Read the full research methodology