What is Spreading Wild?

A spreading wild is a wild that does not stay in the position it landed on. After it arrives it converts adjacent positions into wilds too, spreading outward across the grid — sometimes to the squares directly around it, sometimes along a row or a diagonal, depending on the game. The distinction from an expanding wild is direction. An expanding wild grows along its own reel, filling the column it landed in. A spreading wild moves sideways as well, so it can touch symbols on reels the original never reached. That makes it the more powerful of the two on games paying along lines, because it can complete several lines at once rather than strengthening a single column. How far it spreads is a fixed rule of the game rather than a random amount in most implementations, and the paytable states it. It is also common for the spreading wild to be one of several wild behaviours a feature can select between, in which case which one is active is decided at the start of a round and holds for the whole of it, so it is worth reading which behaviour you have been given before judging the round.