Reactoonz replaces traditional reels entirely with a 7×7 grid populated by quirky alien creatures, where wins form from clusters of 5 or more matching symbols connected horizontally or vertically. Winning clusters disappear and new symbols drop in to fill the space, allowing chain reactions within a single spin. The game’s signature feature is its energy meter: certain symbols charge a meter as they contribute to wins, and once fully charged it awakens the Gargantoon, which triggers one of four random features – ranging from added wilds to a full board transformation – each capable of producing significant additional wins. There’s no separate scatter-triggered bonus round; the Gargantoon mechanic runs continuously as part of the base game, keeping the feature always within reach rather than gated behind a rare trigger. High volatility and a 4570x max win reflect the game’s reliance on stacking multiple Gargantoon activations within a spin. Reactoonz was genuinely influential in popularising cluster-pays grid slots as a category, and its charge-meter structure remains distinctive among Play’n GO’s wider catalogue.