Short answers, pulled from the story.
Tomohiro Nishikado designed the first action game Space Invaders while working as a designer at Taito. He released the game in 1978 in an arcade in Tokyo. This title introduced enemies that could react to player movement and fire back.
Irem released the first influential side-scrolling beat em up game Kung-Fu Master in 1984. The game drew inspiration from Hong Kong martial arts films like Bruce Lee's Game of Death. It allowed players to punch and kick through side-scrolling stages.
Shigeru Miyamoto created Super Mario Bros in 1985 for the Nintendo Entertainment System. The game reinvigorated the North American home video game market after the crash of 1983. It established the conventions of the side-scrolling platformer sub-genre.
Capcom released Street Fighter II in 1991 to popularize direct tournament-level competition between two players. The game changed the social dynamic of the arcade by allowing players to challenge each other face-to-face. This release paved the way for deathmatch modes found in modern action games.
The Namco System 21 and Sega Model 1 arcade system boards originally designed for racing games drove the 3D Revolution in action games. These boards were repurposed to create immersive 3D environments for titles like Virtua Fighter and Tekken. The technology allowed for more complex character movements and camera angles.
Studies conducted by scientists at the University of Rochester revealed that playing action video games improved eyesight by about 20% over a month. Participants playing Unreal Tournament showed better performance in eye examinations compared to those playing Tetris. This suggests that intense visual processing required by action games can sharpen the brain's ability to track multiple moving objects.