There’s mystery lurking between the bars at Hellcatraz. Each Mystery Symbol appears as a countdown, reduced with each cascade. When it reaches 0 the symbol is revealed. Choose between Lockdown Mode or Mixed Mode that start at the same counter values or different ones, respectively. Keep an eye out for Key Symbols that can award 1-10 Keys each, 2000 of them unlock Super Free Spins where Mystery Symbols immediately reveal themselves, and Golden Mystery Symbols trigger additional spins with just 2 cascades!