BoxWorld: Let World Engines Control and Video Generators Render
Organizations: University of British Columbia · Vector Institute for AI · Huawei Canada · Canada CIFAR AI Chair
Abstract
We tackle the challenge of building real-time interactive video worlds with user-defined behaviors. Such worlds must track object states, apply interaction rules, and render the resulting consequences as users act. Yet existing end-to-end video world models typically learn interaction dynamics within the generator, making it difficult to specify object-level rules and reason about their consequences. In this work, we introduce BoxWorld, which separates interaction reasoning from generative rendering. Given user-specified rules, a coding agent creates a Box World Engine that determines interaction outcomes and exposes the resulting object states through a lightweight interface of layout boxes, persistent object attributes, and dynamic status variables, leaving appearance and physical effects to generative rendering. A Box-State Generative Renderer then renders this evolving state stream into video autoregressively, enabling online control over object motion, state switches, and conditional events. Rendering this state stream is non-trivial: the renderer must respond to object-level state updates in real time while remaining coherent with the generated history. To this end, we introduce a three-stage training strategy that learns object grounding from open-domain videos and state transitions from gameplay videos, both annotated automatically, and finally performs rollout distillation on self-generated histories. We further propose PairedStateBench, a paired benchmark for fine-grained interaction control. BoxWorld substantially outperforms end-to-end world models and remains competitive across multiple public benchmarks. Project page: https://boxworld-web.github.io.
Figures & tables
| Method | FPS ↑ | Trigger ↑ | Suppress ↑ | Paired-CF ↑ | State-Fid ↑ | OnTime ↑ | Task ↑ |
|---|---|---|---|---|---|---|---|
| Overall | |||||||
| LingBot-v1 | 0.05 | 53.5 | 11.1 | 16.2 | 43.1 | 44.5 | 25.3 |
| LingBot-v1 (Oracle) | 0.05 | 45.5 | 25.4 | 16.2 | 42.3 | 27.7 | 18.4 |
| LingBot-v2 † | 13.3 | 21.3 | 63.5 | 10.8 | 46.1 | 14.3 | 11.5 |
| LingBot-v2 † (Oracle) | 13.3 | 19.0 | 69.8 | 16.2 | 57.1 | 17.5 | 11.5 |
| LongLive | 20.7 | 10.7 | 50.8 | 13.5 | 36.2 | 5.7 | 8.0 |
| VBench | ||
|---|---|---|
| Variant | Total ↑ | Long Total ↑ |
| Stage 1 | 83.30 | 81.72 |
| Stage 2 | 83.57 | 81.82 |
| Stage 3 | 83.76 | 83.00 |
| YouTube-VIS | ||
| Variant | mIOU ↑ | FVD ↓ |
Appendix figures & tables10 assets
Supplementary material from the paper’s appendix.
Appendix
| VBench | VBench-Long (30 s) | ||||||
| Model | FPS ↑ | Total ↑ | Quality ↑ | Semantic ↑ | Total ↑ | Quality ↑ | Semantic ↑ |
| LTX-Video ( HaCohen et al., 2024 ) | 8.98 | 80.00 | 82.30 | 70.79 | – | – | – |
| Wan2.1 ( Team Wan et al., 2025 ) | 0.78 | 84.26 | 85.30 | 80.09 | – | – | – |
| SkyReels-V2 ( Chen et al., 2025a ) | 0.49 | 82.67 | 84.70 | 74.53 | 75.29 | 80.77 | 53.37 |
| MAGI-1 ( Sand.ai et al., 2025 ) | 0.19 | 79.18 | 82.04 | 67.74 | – | – | – |
| NOVA ( Deng et al., 2025 ) | 0.88 | 80.12 | 80.39 | 79.05 | – | – | – |
| Method | Real-time | FVD ↓ | mIOU ↑ | rCLIP | rCLIP | rCFC ↑ |
|---|---|---|---|---|---|---|
| TrackDiffusion ( Li et al., 2025a ) | No | 464 | 0.492 | 0.273 | 0.804 | 0.940 |
| LVD ( Lian et al., 2024 ) | No | 558 | 0.281 | 0.261 | 0.803 | 0.861 |
| VideoTetris ( Tian et al., 2024 ) | No | 590 | 0.166 | 0.267 | 0.799 | 0.423 |
| BlobGEN-Vid ( Feng et al., 2025b ) | No | 317 | 0.598 | 0.289 | 0.836 | 0.958 |
| BoxWorld (Stage 3) | Yes | 62 | 0.572 | 0.291 | 0.837 | 0.965 |
| Variant | Quality ↑ | Semantic ↑ | Total ↑ |
|---|---|---|---|
| Stage 3 | 84.82 | 79.54 | 83.76 |
| w/o spatial mask | 81.78 | 74.51 | 80.33 |
| Stage 2 | 84.22 | 80.97 | 83.57 |
| w/o dynamics LoRA (Stage 1) | 84.46 | 78.62 | 83.30 |
| High-noise-only LoRA | 83.84 | 77.44 | 82.56 |
| Open-domain video LoRA | 82.68 | 79.16 | 81.98 |
| Variant | FVD ↓ | mIOU ↑ | rCLIP | rCLIP | rCFC ↑ |
|---|---|---|---|---|---|
| Stage 3 | 62 | 0.572 | 0.291 | 0.837 | 0.965 |
| w/o spatial mask | 79 | 0.291 | 0.264 | 0.783 | 0.955 |
| w/o object attributes | 68 | 0.323 | 0.273 | 0.785 | 0.963 |
| Variant | Trigger ↑ | Suppress ↑ | Paired-CF ↑ | State-Fid ↑ | OnTime ↑ | Task ↑ |
|---|---|---|---|---|---|---|
| Stage 1 | 87.3 | 60.3 | 64.9 | 83.4 | 83.8 | 49.4 |
| Stage 2 | 82.0 | 85.7 | 67.6 | 83.6 | 81.5 | 64.4 |
| Stage 3 | 92.2 | 90.5 | 97.3 | 91.6 | 91.2 | 83.9 |
Real-Time Interactive Video Generation
Real-Time Interactive Video Generation creates low-latency video streams that respond continuously to user actions, camera motion, text, or audio.
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