Open-source initiative for open-ended realistic simulation of autonomous agents in physical and social worlds

Joined January 2026
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Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
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SimWorld retweeted
This is one of the coolest things I’ve seen with @claudeai Fable 5. It’s been 1 day 🤯 Impressive👏👏
Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
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SimWorld retweeted
9. Generated the most realistic AI village simulation so far.
Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
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SimWorld retweeted
Generated the most realistic AI village simulation so far. Dense terrain, natural building placement, lived-in details. x.com/simworld_ai/status/206…

Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
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SimWorld retweeted
Generated the most realistic AI village simulation so far. Dense terrain, natural building placement, lived-in details.
Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
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SimWorld retweeted
For me this is the first one that feels believable. Don't trust the wide shot. Verify the closeups.
Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
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SimWorld retweeted
Replying to @simworld_ai
le real unlock here isn't just more detailed textures or better rendering. it's that these models can now generate multiple iterations of a scene in minutes, forcing you to rethink what "good" design even means in the first place
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SimWorld retweeted
Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
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392,142
SimWorld retweeted
Close-ups from Fable 5: Good progress on global aesthetics and scene details: more coherent village layout, rooftops, balconies, water tanks, AC units, stalls, and small props that make it feel lived-in. But still not solved: some buildings are floating above the sand or not properly grounded to the terrain 😅
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Update: also tried the same prompt with Fable 5 First impression: visually the strongest result so far --- denser village, better terrain/building placement, and nice lived-in details. Still not perfect though: close-ups show both good details and failure cases, including floating buildings 😅 (check out the threads👇)
We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
5
14
185
392,142
Close-ups from Fable 5: Good progress on global aesthetics and scene details: more coherent village layout, rooftops, balconies, water tanks, AC units, stalls, and small props that make it feel lived-in. But still not solved: some buildings are floating above the sand or not properly grounded to the terrain 😅
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SimWorld retweeted
Haha, great catch🤣 Opus 4.8 apparently decided palm trees are exempt from physics. At first glance the scene looks great, but the zoom-ins tell a different story: floating trees, upside-down trunks, and palms growing straight out of buildings 🌴
Replying to @simworld_ai
People likely think that Opus version looks better due to the palm trees... yet almost all of these trees are completely bugged. Look how many of them are just floating upside down in mid air or growing out of buildings....
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Haha, great catch🤣 Opus 4.8 apparently decided palm trees are exempt from physics. At first glance the scene looks great, but the zoom-ins tell a different story: floating trees, upside-down trunks, and palms growing straight out of buildings 🌴
Replying to @simworld_ai
People likely think that Opus version looks better due to the palm trees... yet almost all of these trees are completely bugged. Look how many of them are just floating upside down in mid air or growing out of buildings....
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Here’s the zoom-in video😂 The desert vibes are real, but so are the anti-gravity palm trees 🌴
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SimWorld retweeted
Replying to @simworld_ai
People likely think that Opus version looks better due to the palm trees... yet almost all of these trees are completely bugged. Look how many of them are just floating upside down in mid air or growing out of buildings....
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SimWorld retweeted
Vote the best!
49% Claude Code Opus 4.8
40% Codex GPT 5.5
7% Cursor Composer 2.5 Pro
5% Gemini CLI Gemini 3.1 P
281 votes • Final results
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SimWorld retweeted
We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
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We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
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Prompt: Produce a desert ruins landscape with a village. In the desert ruins map, there are ancient ruins strewn across the surface. I want you to scrap those ruins, but keep the landscape, and create a village. Make it feel like a real, lived in urban environment with middle eastern houses placed in a village like grid. Hard Constraints: Make sure to load in the desert ruins map and get rid of the collapsed pillars and columns, just give the base desert dunes (only delete pillars and columns, NOTHING ELSE) Create the desert ruins village with a middle eastern village DO NOT utilize any city buildings to create village component. We want something that has a bit of a "rustic" feel, not a metropolitan one Make sure to spawn at least 50 buildings to construct the village, make it look very dense Up to you: The layout of the houses is up to you. Make it feel like a real village, but utilize the middle eastern village building assets and ensure that those are laid out in a realistic way. The exact, finegrained details of how you lay them out are up to you Adding additional assets. If you want to add additional elements to make the scene better, such as adding flags, plants, roads (dirt roads specifically), that is totally up to you. The only hard constraint is the village creation as well as the desert ruins landscape, all the other elements of the scene (ie exact house layouts, roads, and any assets that make the scene more unique), are up to you/ Feel free to experiment with those additional assets, and make sure the scene feels unique
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SimWorld retweeted
fits my experience. cc is too slow for outsider, and the quality diff, if any in given task, mostly doesn't justify the latency. hope codex could release /slow mode to further push the frontier of (quality, latency, throughput) for humble max subscriber.
We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
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SimWorld retweeted
I think Claude Code may have won on quality, but it came at a cost: 14× the runtime of Cursor. Gemini is interesting here, not the absolute best, but maybe the best balance between quality and speed.
We gave 4 frontier coding agents the same hard environment-gen test: Preserve the desert landscape. Surgically remove only the ruins. Then build a dense, believable Middle Eastern village from scratch using rustic assets. Which model did the best job? 🏜️👇 Poll and full prompt in thread.
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