Ready Player Two? It's not that crazy. Ready Player One is based on the novel of the same name by Ernest Cline (who also co-wrote the movie's screenplay with Zak Penn) and in the lead-up to the film's release, Cline revealed he has already begun writing a sequel to the novel. Just what his sequel will be about remains a mystery for now, but there's clearly much about the OASIS - a virtual world in where people can live out their every fantasy as long as they have the coin to pay for it - that can be explored in not only a sequel film, but potentially an entire franchise.

With a sequel to Ready Player One, the book, already in the works, discussion will inevitably shift towards the possibility of a second film. Of course, that will largely hinge on the film's box office success. Early tracking reports put Ready Player One as having an opening weekend in the $38-$42 million range; a respectable haul, but perhaps a bit less than is expected for a film with little-to-no competition that's opening across a holiday weekend. Still, word of mouth is sure to be what really drives interest in Ready Player One considering it's certified fresh with an 84% on Rotten Tomatoes. Plus, there's no denying the box office appeal of Steven Spielberg and his involvement alone is sure bring in some viewers who would otherwise skip Ready Player One. And while there's no guarantee Spielberg would return to direct a sequel, his handling of the material creates a clear blueprint for future stories which other writers and directors could follow.

Related: How Ready Player One Got All Its Easter Eggs

Beyond the basic plot structure and characters, the film Ready Player One is surprisingly different from the book, with lots of entirely new elements. This makes for an interesting adaptation but it also raises questions about the planned novel and possible sequel film. When discussing his next book, Cline cites working on the film adaptation alongside Spielberg as being what inspired him to continue the story. And with this in mind, it might just be that the differences between the book and the movie are what got Cline's creative juices flowing. In which case, the clues to what a Ready Player One sequel - a Ready Player Two, if you will - could be about may just stem from how the movie's ending is different from the book.

Warning: spoilers for Ready Player One from this point.

Both the book and film end with Wade Watts/Parzival (Tye Sheridan) finding the Easter Egg, gaining control of the OASIS, and beginning a relationship with Samantha/Art3mis (Olivia Cooke). Nolan Sorrento (Ben Mendelsohn), the CEO of the vile corporation, Innovative Online Industries is arrested and the OASIS remains free of corporate oversight and control. The way the movie ends, however, changes the way the main theme of reconnecting with reality and valuing personal relationships over technology is relayed to Wade (and therefore the audience).

In the Ready Player One's ending, Wade isn't simply rewarded by Anorak (Halliday's avatar and orchestrator of the contest) but he comes face to face with Halliday himself - at least, that's how it appears. Wade (as his avatar, Parzival) interacts with a virtual Halliday who regrets not living life to its fullest and ignoring the real world. He shares with Wade the wisdom that "reality is real" and only there can true happiness be found. The scene adds some melancholy to an otherwise victorious ending, but it also raises questions about how it is Halliday can be within the OASIS. Before he died, did Halliday upload his consciousness to the OASIS? Has he found a way to continue living, in at least a virtual form, after death? So much of Ready Player One involves deconstructing Halliday's life for clues - visualized in the film by a massive library with recordings of his every memory - that it doesn't seem such a stretch that Halliday took it one step further and actually put himself in the OASIS before he died.

While the idea of an OASIS-afterlife seems to fly in the face of the message about valuing reality because it's real, exploring the ramifications of just such a concept is compelling material for a sequel to cover. Now that Wade has learned to appreciate reality and the relationships forged there, how far would he go to save the people he loves? If he could save someone by literally saving them within the OASIS, would he?

Related: The Star Wars Easter Eggs In Ready Player One

Cline has made it clear (via THR) that he's trying to "write a sequel to the book and not to the movie," recognizing that the movie has changed things. But the lessons Wade learns are the same whether it's the book or the movie. Were Cline inspired by some of the changes the film makes, it's possible Spielberg hints more strongly at what a Ready Player One sequel could explore than at first it seems. It's like The Lost World: Jurassic Park all over again!

More: Ready Player One’s Cast Is One Of Spielberg’s Best

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