The Thirteenth Floor

For years, Douglas Hall has been working with his friend and mentor, Hannon Fuller, to create a simulated world. Not merely a computer game, their simulation is a Small Secluded World where the inhabitants don't know that they are simulated. They believe that their world is the physically real world of 1937, not just a simulation in a cluster of supercomputers at The Thirteenth Floor of some future skyscraper.

Now someone or something has murdered Fuller, and seem to be trying to pin the blame on Hall. The answer to the mystery is somewhere in the world they created together... But their world is not safe anymore. Simulated humans are awakening to the terrible truth of their existence, wanting revenge on their deceitful creators.

Tropes used in The Thirteenth Floor include:

Bait and Switch Gunshot: The good girl is running away from her mad husband from the future (don't ask), and finds herself in a wide open space with nowhere to go. Said husband lifts his gun and she closes her eyes, ready for the worst. The camera stays on her, there is a bang and she shudders — but a second later she opens her eyes, and we see that the husband has been shot by another good guy instead.
Color Wash: One of the characters comments on the colors being "off" in the simulated world.
Cyberspace: Kinda.
Dueling Movies: A three-way contest - squarely lost in the general public fame - with The Matrix and eXistenZ.
Go Mad from the Revelation: Happens when a bartender from the 1937 simulation finds a letter that leads him to suspect his world is not real. He goes homicidal when he encounters one of the creators of the simulation.
- Douglas has a minor breakdown when he discovers "the End of the World".
Heroic Blue Screen of Death: Douglas Hall upon learning the truth.

Douglas: Yeah, there's just one little flaw in your thesis. None of this is real! You pull the plug... I disappear! And nothing I ever say, nothing I ever do, will ever matter!

Hey, It's That Guy!: Max Baer is Douglas Hall, Detective Goren is Hall's nerdy coworker/the crooked simulation bartender, and President David Palmer is Detective McBain.
Hyde Plays Jekyll
Ignorant of Their Own Ignorance: A certain character in the 1937 world starts out like this, but is brutally awakened to the true nature of reality.
Inside a Computer System: Much of the plot takes place in the 1937 world. The "real world" is also a computer simulation. Eventually the hero gets uploaded to "the real real world" — unless that world is also a computer simulation. The film's ending leaves the interpretation open with the very last scene before the credits.
I Want My Jetpack: a man in the 1990s discovers he's really in a VR simulation of the 90s created in 2024. At the ending he gets to see what 2024 looks like, and the buildings are all bizarre "futuristic" things out of Buck Rogers.
Kiss Me I Am Virtual: One of the characters turns out to have been visiting the 1930's so he can have sex with showgirls (he would have been a teenager in the 1930's, so this fetish is understandable). Goes into What Measure Is a Non-Human? territory because the character he takes over has marital problems when he comes home with no memory and smelling of perfume.
Love At First Sight: Played with. The hero and the girl meet and are immediately attracted to each other; after a brief dance they reflect on the fact that both seem to be already familiar with each other, and the girl says deja-vu is usually a sign of love at first sight - and sure enough, they fall madly in love. It later turns out the girl has been watching him from the start of the simulation, and has been in love with him for a long time; he, instead, has been modeled on the girl's husband, and has had regular memory interference from him - hence the familiarity.
Prop Recycling: The crew reused the set for Deckard's apartment from Blade Runner for Hall's apartment. The furniture is different, but the patterned wall tiles are unmistakable.
Recursive Reality: Worlds within worlds.
Schrödinger's Butterfly: What is real and what is the simulation?
The Future Is Noir: As is the present, and the past. It's safe to say that this is one of the noir-iest movies ever made.
World Limited to the Plot: Deconstructed, as this plot is actually about writing reality itself.
Your Mind Makes It Real: You enter a virtual world by possessing one of its inhabitants, and if killed in this state, your mind dies. And not only that, but the victim's mind is transferred to your body instead.
- It was more a case that simply entering the virtual world caused the swap, with the virtual person's mind entering your real world body even as your mind entered their virtual body. No one realized this, however, because the real body usually remained completely unconscious during the process. Virtual death merely broke the connection and jarred the real world body with the virtual mind inside it awake.
What Happened to the Mouse?: Grierson, loyal husband and very innocent in all the mess, is - from his perspective - unceremoniously dumped at the table by the person who got him there, who then never returns. So Grierson is left in the middle of the place where his alter ego used to go to have sex with the girls and everyone knows him and what "he" does, but he doesn't know anyone - though he has faint memories of what his alter ego used to do. And while Hall is busy doing his things, the poor guy must be feeling like he's losing his mind.