Easytoon was created at the basis by Takahashi Keijiro from Radium Software in its version 1.0 in 1998
This simple program allows the User to create a sequence of images- then convert the images to create a moving Animated GIF, thus the frames give the illusion of movement. And though most of the gifs are in monochrome - some are colored; likely with Paint or another art prog.
The gifs are easy to recognize by their line texture.