The earliest build of Luigi's Collision Problem. The original project was simply named "mario engine". Jumping was completely scrapped in the actual game, however, it'll return in version 3.0 of the game as a special ability at a certain point in the game.
This can't be played on mobile. Use the left and right arrow keys to move around, use the up arrow key to jump, and the down arrow key to duck. You can also change the "level" by pressing the space key.