Algodoo

This scene is made up with ton of "suns". They represent solar clusters, which after a while, (almost) all of them collide and make up a big galaxy.
If I know to make a script which randomly puts "suns", this will be more awesome. This is an example how Milky Way can be formed.

Different color means different clusters of galaxies. Note that (example) that a blue "sun" can collide w/ the green "sun". Also, note that the clusters mainly collides with their other "suns" first, then with other.

v0.3 - Colored the suns to (mostly) show the clusters of galaxies.
v0.2 - moved suns which causes to shoot themself away
v0.1 - First release