Sticky Wild Slots
A sticky wild stays in its cell for a stated duration and substitutes on every spin it survives, most often inside free spins or respins.
How sticky wilds work
A sticky wild is a Wild Symbol that remains in its cell after the spin that landed it. The symbol then substitutes on every following spin whilst it stays, and the duration is a rule of the specific game. Common durations are the remainder of a bonus round, a stated number of spins and the length of a Respins sequence.
The effect lives mostly inside features. A sticky wild across a full Free Spins round changes the value of every remaining spin, which is why games place the behaviour there rather than in the base game. Base game versions exist and usually hold the symbol for a short, stated stretch.
Stickiness interacts with the win system underneath. On lines the held wild keeps completing the same paths, and in cluster or counting systems it keeps feeding groups as new symbols arrive around it. Where several sticky wilds accumulate, the rules should state whether the count is capped and whether new arrivals refresh any timer.
The paytable lines that define the feature are short. They are the trigger, the exact duration and the interaction with other wild variants, since some games let a held wild expand or carry a multiplier as well. A stated duration is the heart of it, because a wild that stays is only worth what its stay is defined to be.
The feature is sometimes advertised simply as wilds that remain, with the duration left vague. Vague is the wrong register for a rule book, and a game that declines to state the stay has left its best feature undocumented.