A Quick Look
Inception is hard to classify. Most critics - and even the studio - seem to call it a "sci-fi actioner", but really, that's a description of the movie's trappings, not what kind of movie it really is. The structure of the film has layer upon layer, and so does the genre:
Inception is a heist movie, where Dom Cobb (Leonardo DiCaprio) gathers a hand-picked band of specialists to pull off an impossible crime. They've got a plan, and of course the plan goes wrong, forcing them to improvise.
Inception is a psychological thriller As we travel farther and farther into the dream world we go deeper into Dom Cobb's mind, getting a deeper look at him, his past, his fears, and what makes him who he is.
Inception is a Shakespearean tragedy, where all the misfortune ultimately extends from a bad decision by the protagonist.
After you leave the theater, if you think about it enough, it's kind of a horror film.
Steal This Idea
The obvious thing to steal from this movie is the idea of stealing an idea from someone's mind, whether that's by dream-sharing, some kind of telepathic probe, or even cyberbrain hacking a la Ghost in the Shell. The main setup with its band of specialists engaging in espionage missions is certainly conducive to a group of PCs, each with a specialized role in the group. You could certainly play an entire game on this level: planning twin capers to not only get access to the target but also how to get into their mind and get the necessary information. If you're going to play on the surface level of a heist film, I'd recommend a system geared towards action: Spycraft comes to mind, if you don't mind the mechanical complexity. At this level the dreaming/mindhacking technology is mostly just a McGuffin.
Going deeper than that would require a group of players who want to really explore their characters - players who would be willing to create flawed characters and confront that during play. I'd recommend a game that talks about those flaws right on the character sheet so that there's some mechanical bite to the characters confronting whatever it is they need to deal with. FATE is one of my go-to games (specially with the recent release of the Dresden Files RPG) and I think that Aspects (both of PCs, and the ability to place them on scenes or locations) could be a powerful tool for handling this type of game.
For the truly ambitious, reality and the dream world (or even the different levels of the dream world) might even use different rules.
The dream-sharing technology (and some of its risks) is similar to that in Roger Zelazny's "He Who Shapes" (a Nebula-winning novella later expanded as The Dream Master).
The RPG Lacuna Part 1: The Creation of the Mystery and the Girl from Blue City deals with similar themes - both invading someone's dreams and the nature of reality.
Another RPG, JAGS Wonderland, has "levels of reality" threaded through it, becoming stranger and more abstract the deeper you go.
Last, I would be remiss if I didn't mention Fred Hicks' Don't Rest Your Head, another game that plays with the boundary between dreams and reality.
There is one big difference between the three RPGs that I mention and the film itself: all of these games are surreal horror, which Inception decidedly is not: the film manages to dodge any Jacob's Ladder-esque diversions into bizarreness. Any strangeness in the dreamworld has a direct and proximate cause, which is part of what pulls us in and lets us, like the dreamers and their target, believe in what is going on.
Wrap-up & Rating
For non-game reviews, I rate on two scales: entertainment (how much I enjoyed the subject as an example of whatever it is) and inspiration (how good it is as fodder for a game.)
Entertainment: * * * * *
This is the best film I have seen this summer. Most science fiction movies are westerns or fantasies in disguise, but this is the real thing; it postulates an advance in science and then considers how it would affect us. The fact that it manages to be an excellent action movie and an interesting character study at the same time is a testament to the ten years of work Nolan put into writing and directing the film.Inspiration: * * *
There's a lot of good ideas in the film, but I think you would need a very particular group to go anywhere past the surface level, and that is where the real power of the movie lies.