This is something quite noteworthy in the context of video games itself.
Both cartoons and videogames are American forms of art.
Early Japanese cartoons in general were VERY similar to Disney's or Fleischer's earlier works, both in the way they looked and the way they were animated. But when the Japanese cartoon market exploded during the 60s or 70s, they tried to find ways to reduce the production cost, much like what Hanna Barbera did for the Flintstones in the US.
Among the methods most widely in use in later anime were moving the characters across the screen without actually changing (= animating) the character's pose (i.e. during a jump or flight); or giving the impression of a fully animated character by only animating the character's mouth or hand, etc.
These methods then were applied to early Japanese video games like Taito's Space Invaders, Namco's Pac-Man or Nintendo's Donkey Kong. It allowed graphic designers to actually animate something that resembled real cartoon characters by changing only a few pixels each frame.
Space Invaders & co. did not feature simple geometric shapes like in Pong or Missile Command, or abstract vector graphics like in Asteroids, Ballzone or Tempest, but something that almost looked like real hand drawn cartoon characters - like the aliens in Space Invaders, the ghosts in Pac-Man, or Donkey Kong and Mario - all of which appear to be fully animated although their entire range of moves consists of only two or three individual frames.