A grid slot uses a larger, often square, playing area instead of the classic five reels and three rows. Grids such as 6x5, 6x6 and 7x7 are common, and they usually pay through cluster pays or pay anywhere rules rather than paylines.
With more positions on screen, grid games lean heavily on cascading reels: winning symbols disappear and new ones fall in, so one spin can produce a chain of wins. Features often add multipliers to grid positions or expand the grid itself; see grid expansion.
Grid slots can feel busier and more generous because of all the small chain wins, but the maths is set to the published RTP like any other game. Many are high volatility, with most of the return concentrated in features.