Published in 1895, The Time Machine is an adventure tale that introduces us to the science fiction of the time machine, and is also an adventure tale about the Eloi and Morlocks in the year 802,701 AD. Many of the concepts in the novel are an imaginative expansion of Thomas Huxley's ideas about entropy and decay in society.
Published in 1898, War of the Worlds is the first novel that ever explored the idea that other planets not only have intelligent life, but that those life forms might engage the people of earth in less than friendly interaction. Aliens land on British soil, and that leads to themes of interplanetary imperialism, technological holocaust and chaos. (Here's a helpful link to a site that discusses the Orson Welles radio broadcast in 1938.)
And here's a link to some strong review format H.G. Wells quizzes.
