Reactoonz is one of Play'n GO's most distinctive slots, featuring alien creatures on a 7×7 grid that operates entirely on cluster pays — no paylines, no rows, just groups of five or more matching aliens touching horizontally or vertically. Released in 2017, it predates the cluster pays boom and remains among the most creative executions of the format.

The eight alien species fill the grid with varying symbol sizes and values. The Gargantoon wild — a large 3×3 alien creature — is the game's most powerful symbol and the ultimate goal of the Quantum feature, which is the heart of Reactoonz's design.

The Quantum feature operates through a charge meter that fills as winning clusters land in the base game. At four different charge levels, the meter triggers one of four Quantum effects: Implosion (two to six random symbols become wilds), Incision (a wild is placed in the centre of the grid with lines of wilds extending to the edges), Alteration (one alien type transforms into another), and Demolition (all low-value aliens are destroyed). The Gargantoon itself activates when the Quantum meter charges to the maximum, placing a 3×3 wild on the grid that splits into multiple smaller wilds across consecutive reactions.

The alien aesthetic — big-eyed, colourful creatures reacting expressively to wins and losses — gives Reactoonz a personality that distinguishes it from the abstract grid designs of many cluster competitors. The combination of the Quantum mechanic, the Gargantoon, and the cluster pay structure creates a game that rewards consecutive sessions for players who enjoy learning the interaction between features.