I haven´t read anything by George R.R. Martin before so The Sandkings was a nice surprise. I guess the best way to tell it is him is the naming of the characters. Some of those names sure have to have come from the mind who thought up “Tyrone Lannister” and such.
It´s a tale about a god complex, treatment of animals and I guess also responsiblity over children and them growing up when you think about it.
It´s set on a distant planet colonised by humans in the future, I guess (looks like he has more stories set in that universe) and is about a very cruel guy who buys the titular Sandkings (intelligent bug like creatures who have a tendency to worship humans) to keep in a big tank in his home for fun. At first he wants them to have war among each other for his sake but eventually ends up feeding them friends of his. But when they break out and grow at a rapid pace chaos ensues.