I am interested in it --
1. These two groups also have event:
"For each SoundLauncher: play FootmanDeath".
2. These event are all executed after "create sprite", the different is the timming of "create sprite".
3.a 1st group only pick created sprite.
3.b 2nd group pick all existed sprite.
It seems 2nd "create sprite" does not change the SOL, so that pick all sprites in "For each".
That's why the 1st group will not crash -- it only play 1 sound each time.
Maybe a tutorial to introduce the rule of setting SOL is necessary. It is implicit to me, too.