1934 and 1935 with an honorable mention to 1954. Virtually every significant innovation in modern pinball had its genesis in 1934/35: ramps, kickers, habitrails, elevated transporters, subways, lights, bells, bonuses, gobble holes, multipliers, you name it.
1954 was an exceptional year for woodrails, universally recognized among pinball historians.
Naturally, pinball manufacturers released many noteworthy games in the decades to follow. Nevertheless, 1934/35 was the springboard of genius which created the hobby.
