The 1940s.
The first pinball table with flippers was introduced in 1947. It dramatically increased player interactivity, transforming it from a game of luck into a game of skill.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.