GameNGen is a research model that generates a playable-looking simulation of 1993’s DOOM by predicting each frame from recent frames and player actions. Its authors report that it ran at 20 frames per second on a single TPU. The headline phrase “hallucinate a game” is shorthand: GameNGen generates images that imitate gameplay; it does not run DOOM’s original code or preserve the game’s exact internal state.
What GameNGen does
GameNGen is a learned visual simulation trained to reproduce gameplay from the existing game DOOM. Instead of executing the game’s hand-written rules, it predicts what the next screen should look like given recent screens and the player’s inputs. The authors describe the work in “Diffusion Models Are Real-Time Game Engines”, first submitted on August 27, 2024, revised on April 24, 2025, and listed as an ICLR 2025 paper.
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That distinction matters: a generated frame may look like a plausible continuation without representing the original game’s exact state or mechanics. The model is an imitation learned from gameplay trajectories, not a replacement executable for DOOM.
How the model generates gameplay
The system uses a two-stage pipeline. First, the researchers train a reinforcement-learning agent to play DOOM and record its observations and actions. They then adapt Stable Diffusion v1.4 to predict the next frame from a short history of frames and the player’s inputs.
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- Gain access to the latest demon-killing Tech with the DOOM Slayer's advanced praetor suit, including a shoulder-mounted flamethrower and the retractable wrist-mounted DOOM Blade
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- Battle mode is the new 2 versus 1 multiplayer experience built from the ground up at id software
- Collect gameplay: An agent plays the game, producing sequences of observations paired with actions.
- Condition a diffusion model: The researchers adapt Stable Diffusion v1.4, remove its text conditioning, and represent player inputs as action tokens.
- Generate the next frame: The model uses recent frames and actions to predict what appears next. That generated image becomes part of the context for the following prediction.
Because each prediction feeds into the next, visual errors can accumulate. The authors added noisy-context augmentation during training to help the model cope with the imperfect frames it will encounter when generating sequences. They also note that conditioning on a stream of actions available during generation challenges assumptions made by existing diffusion architectures.
What the reported results show
The following figures are the paper’s reported experimental results, not guarantees about every play session or hardware setup.
Rank #2
- Developed by id Software, DOOM: The Dark Ages is the prequel to the critically acclaimed DOOM (2016) and DOOM Eternal that tells the epic cinematic origin story of the DOOM Slayer’s rage.
- In this third installment of the modern DOOM series, players will step into the blood-stained boots of the DOOM Slayer, in this never-before-seen dark and sinister medieval war against Hell.
- A dark fantasy/sci-fi single-player experience that delivers the searing combat and over-the-top visuals of the incomparable DOOM franchise, powered by the latest idTech engine. With a customizable difficulty system, it’s the perfect entry point whether you’re new to the franchise or a long time fan.
- As the super weapon of gods and kings, shred enemies with devastating favorites like the Super Shotgun while also wielding a variety of new bone-chewing weapons, including the versatile Shield Saw.
- Experience the origin story of the DOOM Slayer’s rage in this epic, cinematic, and action-packed story.
| Measure | What the authors reported | What it means |
|---|---|---|
| Generation speed | 20 frames per second on a single TPU | A research-system result on TPU hardware; it does not establish performance on a consumer PC or console. |
| Next-frame prediction | 29.4 PSNR | The paper compares this image-quality measure to lossy JPEG compression. It evaluates predicted frames, not whether the whole game behaves exactly like the original. |
| Short-clip ratings | In comparisons by ten human raters, the real game was selected in 58% of trials for 1.6-second clips and 60% for 3.2-second clips. | These results concern brief clips and a small rater group; they do not show that the simulation is indistinguishable in general play. |
| Ratings after extended play | In three-second comparisons after 5–10 minutes of gameplay, raters selected the real game in 50% of trials. | The authors also note that people familiar with the simulation’s limitations could often spot the real game after a few seconds. |
What it cannot establish
It does not run the original DOOM engine
GameNGen learns a visual response from recorded trajectories. It does not execute DOOM’s original code or maintain its exact internal game state. The paper describes the simulation as non-exact, so similar-looking frames should not be mistaken for proof that all game rules and interactions are reproduced faithfully.
Its working context is short
The model’s context contains 64 frames, which the authors describe as a little over three seconds of history. They say that extending the context would likely require changes to the architecture or training scheme. A short visual history can make continuity and longer-term state harder to preserve than in a conventional engine that explicitly tracks game state.
Rank #3
- Developed by id Software, DOOM: The Dark Ages is the prequel to the critically acclaimed DOOM (2016) and DOOM Eternal that tells the epic cinematic origin story of the DOOM Slayer’s rage.
- In this third installment of the modern DOOM series, players will step into the blood-stained boots of the DOOM Slayer, in this never-before-seen dark and sinister medieval war against Hell.
- A dark fantasy/sci-fi single-player experience that delivers the searing combat and over-the-top visuals of the incomparable DOOM franchise, powered by the latest idTech engine. With a customizable difficulty system, it’s the perfect entry point whether you’re new to the franchise or a long time fan.
- As the super weapon of gods and kings, shred enemies with devastating favorites like the Super Shotgun while also wielding a variety of new bone-chewing weapons, including the versatile Shield Saw.
- Experience the origin story of the DOOM Slayer’s rage in this epic, cinematic, and action-packed story.
New-game creation remains a proposal
The authors suggest that future systems might use text or example images to create or edit game content, but they had not experimented with those directions in this work. This study therefore does not demonstrate arbitrary game generation, commercial readiness, or replacement of conventional game engines. The paper’s authors call GameNGen “a proof-of-concept for one part of a new paradigm where games are weights of a neural model, not lines of code,” while emphasizing that important questions remain and the proposed directions were not tested.
Can you play GameNGen?
The cited paper and the accompanying Ars Technica report describe a research demonstration, not a consumer release. They do not establish a public download, supported consumer hardware, or a product you can install and play. The paper’s single-TPU speed result is not a consumer hardware recommendation.
Rank #4
- A Relentless Campaign: There is no taking cover or stopping to regenerate health as you beat back Hell's raging demon hordes
- Return of id Multiplayer: Dominate your opponents in DOOM's signature, fast-paced arena-style combat
- Near-Limitless Gameplay: Doom SnapMap – A Powerful, but Easy-to-Use Game and Level Editor That Allows for Limitless Gameplay Experiences on Every Platform
- Entertainment Software Rating Board (ESRB) Content Description: Blood and gore, intense violence, strong language
How it differs from a conventional game engine
A conventional engine runs programmed rules and maintains explicit state; GameNGen learns to generate visual outcomes from observed gameplay. That makes the demonstration interesting as a new kind of simulation, but the available paper does not offer a controlled cost or performance comparison with commercial engines. The evidence also does not establish comparable handling of long-term or off-screen state, consistency over extended play, or support for games beyond the trained DOOM simulation.
Quick Recap
Best Value
- DOOM + DOOM II on a region-free physical disc.
- Includes: DOOM, DOOM II, TNT: Evilution, The Plutonia Experiment, Master Levels for DOOM II, No Rest for the Living, Sigil & Sigil II, Legacy of Rust (a new episode created in collaboration by id Software, Nightdive Studios and MachineGames).
- A new Deathmatch map pack featuring 25 maps
- Total of 187 mission maps and 43 deathmatch maps in DOOM + DOOM II
- # of Players: Single System 1-4, Local wireless 1-8, Online 1-16
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