Gottlieb's Humpty Dumpty, introduced in 1947, was the first game to add player-controlled flippers to keep the ball in play longer, adding a skill factor to the game.[4] The low power flippers required three pairs around the playfield to get the ball to the top.
Triple Action was the first game to feature just two flippers at the bottom of the playfield. Unlike in modern machines, the flippers faced outwards. These more powerful flippers were facilitated by the addition of a DC power supply. These innovations were some of many by designer Steve Kordek.
The first game to feature the familiar dual-inward-facing-flipper design was "Spot Bowler," made by Gottlieb in 1950.
The post-war era was dominated by Gottlieb. Game designer Wayne Neyens, along with artist Leroy Parker, produced games that collectors consider some of the best classic pinball machines.