'Juggle Jam' is more of a toy than a game. It's based on some mathematical theory behind juggle patterns. It has been made in 48h during LDJAM 40.
You can :

load premade juggling patterns
create your own juggling patterns using a dedicated in-game editor
create a random juggling pattern and let it hypnotise you

If you know how to juggle, you can try to follow the motion and the patterns.
Let me know if you have managed to reproduce some patterns with real balls.
Time spent during the jam actually juggling instead of coding : too much
Controls :

keys C and V and arrow keys
return : menuhelp
In play mode :
c:toggle view
v:go to editor mode
In editor mode :
c:grab a ball or a throwing node
v:go to play mode

This idea was inspired by a video from Numberphile, you can check it if you want to know more about some math theory of juggling :
https:www.youtube.comwatch?v=7dwgusHjA0Y
You can find the Ludum Dare page here :
https:ldjam.comeventsludum-dare40juggle-jam