Hello,
Nostalgic, this bring me back 20 years ago, when I was starting to learn electronics in Cameroun
whit analog component without any micro-controller unit.
There was also a variant, you can remove the CD4017 and all the LEDs and place a buzzer or a High speaker to the output of the NE555 to make some song. By combining the modify circuit with some external material I was making a very chip alarm to place in a door or a windows
Thanks for this post.