The crown is the wild symbol and it will substitute for all of the other symbols, except for the scatter symbol, to help and form more winning combinations.
The scatter symbol is a gold coin featuring the multi-headed Hydra.
On any spin, any of the symbols, except for the scatter or wild, can appear charged. The charged symbols then lock Power Zones on the positions they land on. The Power Zones can connect with each other horizontally and vertically, and landing another charged symbol next to a Power Zone expands the zone. When a charged symbol lands within a Power Zone, all symbols in the zone transform into the charged symbol, to help and form more winning combinations.
There are four Hydra features that are progressively unlocked as you play. At first, the first feature is unlocked and the other three features are unlocked by filling the meter above the reels. The meter is filled by landing charged symbols in a Power zone. Each time that a feature is unlocked, a free respin is awarded with the unlocked feature activated. The first feature adds up to 11 wild symbols on reels two to six on any spin. The second feature adds up to 9 extra Power Zones on any spin. The third feature adds up to four Multiplier Power Zones on any spin with a x2 multiplier. The fourth feature adds up to three extra Power Zones on any spin and transforms all Power Zones into a mystery symbol. After all features are unlocked, filling a meter again awards a free spin with a randomly chosen feature.
The Mighty Hydra Free Games begin when at least three scatter symbols land on the reels. Landing three, four, five or six symbols awards 12, 18, 25 or 50 free spins respectively. During the free spins, landing two more scatters awards three more spins while three, four, five or six scatters will award 12, 18, 25 or 50 more spins. This way an infinite number of free spins can be won. When the spins begin, the triggering scatter symbols will create Power Zones on their positions and these remain in place for the duration of the spins. At the end of the spins, a Mega Spin is awarded in which all symbols in the Power Zones transform into the same randomly chosen symbol to hopefully form a big win.
The king and queen symbols both offer the top payout of 28x when six land across the reels while all of the other character symbols can payout up to 24x. The gem symbols can all payout up to 20x.