Because of the huge reach of Mad they were popular before but they felt more like mediocre filler content within Mad. Yes the style was distinct but the plot was always the same and predictable. With the games they found their real determination: the visual style, the always recurring topic of the spies tricking each one into a trap--the games were the perfect media for Spy vs Spy, way better than the strips.

And it was more than a handful of games. Spy vs Spy was a strong merchandise running over many years with an unique and innovative gameplay then for many platforms.