A gaming device having a free spin mode or sequence with terminators and anti-terminators. For each spin or activation of a plurality of reels in the free spin mode, the gaming device determines if at least one terminator symbol or at least one anti-terminator symbol is generated. If at least one terminator symbol is generated and at least one anti-terminator symbol is not previously retained, the free spin mode ends. If at least one terminator symbol is generated and at least one anti-terminator symbol is previously retained, the retained anti-terminator symbol is utilized to nullify the free spin ending effect of the terminator symbol and the free spin mode continues. If at least one anti-terminator symbol is generated, the free spin mode continues and the generated anti-terminator symbol is retained or accumulated until a terminator symbol is subsequently generated on another spin or activation of the reels. The free spin mode continues until at least one terminator symbol is generated and there are no retained anti-terminator symbols to nullify the effect of the generated terminator symbol.