Provide that they have enough chemical knowledge.....they would have done it already.
Still, I was expecting a meltdown light show instead of "bloom".
True, but at least the developer can avoid any frivolous lawsuits by not giving the correct recipe. As for kids having the correct recipe, there's nothing to do to stop it then. However, I really doubt most kids that are dumb enough to try burning things with thermite would be smart enough to know how to make it.
As for the effect, I'm usually disappointed with explosive effects in video games and movies. Everything needs to be a massive fireball of an explosion for some reason...