Cluster pays slots don't have paylines. You win by landing a group of matching symbols that touch horizontally or vertically, usually five or more. Winning symbols are then removed and new ones fall into the gaps, which can lead to more wins on the same spin.
Of the 78 slots here, 31 come from Hacksaw Gaming and 25 from Pragmatic Play, and 72 have free spins. Pragmatic's Sugar Rush and Fruit Party games use 7x7 grids where winning positions are marked, and repeat wins on those positions build up multipliers. Hacksaw's Le series, including Le Bandit, Le King and Le Fisherman, uses 6x5 grids and bonus rounds that improve with each extra scatter.
30 of the 78 are medium volatility, which suits players who want a steadier pace. Sugar Rush Super Scatter has the highest listed max win at 50,000x.