GURPs steampunk is an addition to the GURPS role playing game, so you will need the GURPs basic set to play it. Remember it is a game, not a novel. It is a description of an alternative world based on steam technology: There are steam computers (called difference engines), steam tanks (landships), sentinent animals (as in H.G.Well's Island of Dr Morreux), submarines, steam moles, huge guns that can fire a spaceship to the moon, etc, etc. All set in the Victorian age of chivalry and corsets. Jolly good stuff, what!