Commander Keen 1 online DOS game is the first of a series of single-player side-scrolling platform video games. The series follows the homonymous Commander Keen, which is the secret identity of the eight-year-old genius Billy Blaze, as he defends the Earth and the galaxy from alien threats with his homemade spaceship, rayguns, and pogo stick. Most of the gameplay features Commander Keen, the player’s character, from the side while moving on a plane. The levels are composed of platforms on which the player can stand, and some platforms allow Keen to jump up from a platform to the other. The player can also move horizontally and he can also use a pogo stick to bounce and jump higher than they can normally with the correct timing.
Wikipedia: https://en.wikipedia.org/wiki/Commander_Keen