The creators of “Westworld” are playing the long game, and that means a win for viewers, although not without a degree of work.

The second season of the science fiction series, based on the 1973 film by the late Michael Crichton, raises the stakes exponentially as the “hosts” of the experiential futuristic amusement park for people who are rich enough to pay for a fantasy vacation revolt against their human masters. The series, created by Jonathan Nolan and Lisa Joy, returns with a 70-minute season premiere on HBO on Sunday, April 22.

The first season ended with an uprising by the hosts. Season 2 picks up with the aftermath: Dolores (Evan Rachel Wood) is working to build an army to secure dominion over the humans, Maeve (Thandie Newton), a host sex worker, opted against escaping Westworld last season in order to find her daughter; and Bernard Lowe (Jeffrey Wright), who was belatedly revealed as a host at the end of last season, struggles with the reality of who he really is throughout the first half of the new season.

Those are just the major story lines. As fans already know, there are plenty of smaller tributaries as well, which sometimes seem detached at first from the main plot, but nothing is without purpose in “Westworld.”

The first of the five episodes made available to critics for review is more than sufficiently gripping, but it’s also very useful. If you can’t quite remember all the details of the first season (and who could? Only an android), the premiere catches you up so seamlessly you won’t even noticed that you’re being tutored.

The most important element about the first season to recall is that the hosts — at least the characters who are known hosts — began to evolve beyond their programmed stories. As robots, they are not supposed to have human feelings, but as they repeat their routines over and over again for the amusement of their rich guests, they begin to feel the stirrings of emotion and unprogrammed reaction to outside stimuli.

There is plenty of action and violence in the first half of the season, but what will empower the show’s longevity is its metaphysical theme, the exploration of the meaning and definition of human existence. What are we beyond a collection of living cells and seawater? As humans, we know we are the accumulation of experience, emotions, hope, regret and fear. For many of the guests and humans in “Westworld,” the process of accumulation has resulted in moral indifference of the most extreme variety and at the expense of the ability to love, to forgive, to hope.

The hosts are not alive in the same sense. They are machines — exceptionally complicated machines. They can be programmed to say or do what humans do; they have been programmed to fake love, hate, desire. What is the difference between experience as a factor in human emotional development and repetition of human-like emotions in hosts? Is it the soul? If so, can that, too, be replicated?

The second season also includes the first major expansion of the “theme park.” Westworld began with a replica of an Old West setting. But there are other “worlds” in the park, and we enter one this season, the Shogun World. It’s a big deal in the show, but perhaps a more worrisome development is the discovery of the body of a tiger rotting on a riverbank. The animal is from another Westworld subdivision, but almost in passing, we learn that inhabitants of the jungle world have never been known to escape before.

We take it in stride, but the carcass shows up later on, just briefly. Stand back from that and consider it within the context of the rise of the robots: What passes for the natural order of things in the dystopian future is coming undone. The laws of nature, as it were, are breaking because the order of things is being upended, and it’s that awareness that informs the action of the story lines and, of course, the violence.

We can easily just follow the surface of the story and find “Westworld” terrifically entertaining. But even if we are not immediately conscious of the thematic aspirations of the series, at some point, we find ourselves considering what it all means — and not just in future tense.

David Wiegand is an assistant managing editor and the TV critic of The San Francisco Chronicle. Follow him on Facebook. Email: dwiegand@sfchronicle.com Twitter: @WaitWhat_TV

Westworld: Sci-fi drama. Season 2 premiere. 9 p.m. Sunday, April 22, HBO.