Sparky&Shortz Hidden Joules

Play'n GO's Sparky and Shortz Hidden Joules continues the story of the endangered planet Alpha Labori and the two robots working to save it, but rebuilds the original's mechanics around cluster pays instead of a payline structure. Hidden Joules moves onto a 7-reel, 7-row grid, and wins now require a connected cluster of at least five matching symbols rather than a line running left to right.

Eight regular symbols make up the paytable. Five coloured gem tiles sit at the low end, paying 15x to 25x the stake for a cluster of 25 or more, while three alien-themed high symbols pay considerably more - 100x to 250x for the same cluster size. Six separate wild symbols are in play: a basic wild, four special wilds each carrying a different grid effect, and a Mega Sparky wild unlocked after collecting four of the special wilds, which noticeably lifts the game's hit rate once active.

Clusters of Alien or Crystal symbols arranged in a 2x2, 4x1 or 1x4 block transform into Mega Symbols, which continue to count as four connected tiles for future wins and add +1 to a Win Multiplier capped at x25 each time. A separate Boost Meter fills as winning combinations land and moves through four stages - +2, +3, +4 and +5 - that determine how much each Mega Symbol transformation adds to the multiplier; once the multiplier hits its x25 cap, the Boost Meter stops contributing.

Three Power Cell scatters on reels 1, 3 and 5 open the free spins round, awarding 10 spins with the Boost Meter running throughout. A further three Power Cell scatters inside the feature add another 5 spins, up to a maximum of 100.

Numerically, Hidden Joules sits below its predecessor in some respects and above it in others: a lower 6,000x maximum win against the original's 10,000x, but a calmer Medium/High 7-out-of-10 volatility rating and a default RTP of 96.20% (down to 84.20% in reduced markets) that lands close to the first game's figures. Bets span 0.10 to 100 per spin, and the sequel released on 28 June 2023.