So I had an interesting idea for an area in a setting wherein rampant Wild Magic has left the area in a state of permanent reversed gravity. I could envision livestock, wild animals, even people wandering into the region and just floating off into oblivion, where various airborne predators could just pick them off. Enterprising individuals would have set up cable-car like tether lines for safe transport through the region and protection from predators, for a cost of course. Then I got to wondering how this would work mechanically and more importantly how the ground itself would not just float away and leave a massive crater at this site. The easy answer to this of course is that it is magic and real world physics need not apply, but I'm just not satisfied with that answer.

So I went back to the drawing board, wanting a region that would be visually unique, interesting, and dangerous. I then settled on the idea that instead of a full reversal of gravity that a once great city has instead been lifted from the earth and left to hang upside-down in mid-air. This would still provide an interesting visual effect, as well as nesting grounds for various flying predators, whether harpies taking up residence inside the building, or say, wyverns nesting atop the floating structures. Could also have the chance for bits of wall, roof, or even furniture to fall from the ruins onto anyone traveling through (under) the ruins.

Does anyone have any input on either of these ideas, any helpful suggestions, or interest in playing in a setting featuring a region like this?

But that field seems very interesting to play with. Especially dealing with all of the flying creatures that just have such a huge advantage over you

Well, if you want stuff to fall up, simply have some note that it doesn't affect the ground - anything not attached to the earth goes up. But the "world" does not. (Or perhaps, the world itself is what flipped. Things still fall "down." Not toward that massive earth as modern gravity would suggest, but rather towards whatever predetermined "down" there was.)

What impact would this have on flying creatures? In either the world where everything goes up, or just under the flipped city, would flying creatures have any problems? After all, they are used to certain gravitational effects. At the very least they might be disoriented if not native to the area.

For the flying flipped city - has anything come to live on top of the now upside down city? How much of the "undercity" was pulled up, and what remains in the ground? For example, are sewer tunnels now exposed on the sides of the ground that is above (but used to be below) the city? What nests in those? Did people survive in the city and continue to live there, only now using their ceilings as floors? Living on what?

How long ago did it happen?

What about water? Are there any water sources up top? fantasy artists seem to love waterfalls coming off of floating rocks.

If you did go with everything floating up you would need to figure out where it goes. How far up does it go? Does it disappear? Is there a massive layer up there somewhere of collected debris? Is it now creating shadows/cloud cover? If people float away what happens to them? (If those on the ground don't know, you still need to!)

Interesting.

I honestly hadn't even put any thought into the underbelly of the city and how that may come into play in a floating ruin, that makes an interesting point.

I had not decided how far things float, if they just float on until they reach orbit, float until you're eaten, or just float to a glass ceiling of sorts and have to find a way back down.

The original inhabitants of the city are long gone, no one stuck around very long after their homes, shops, and taverns all flipped upside down in the sky.

In the timeline of things, I'd say it happened likely a century or so before the start of the current era in the setting, so it has been that way for a while.

I suppose rain water could still pool in the floating masses and provide the occasional trickle of water from above, wells or water lines though would be cut off from water supplies.

I'm picturing ruins kinda like these only upside down so the buildings and such are pointing at the craters left behind by the city foundations being forcefully lifted. Granted after a century or so the "craters" would now be lakes, if not marshland with scattered deep pits of stagnant water (and who knows what lives in those?)

Maybe instead of no gravity it has an area of reduced gravity like on the moon. Water, rocks and rooted items would not be effected because they all eventually settle back to the ground. Livestock and people would find walking difficult due to the effects of normal pushing motion causing them to "float" for a time before coming back down slowly. Flying creatures might be able to move faster than expected upwards for an attack but slower downwards as gravity doesn't aid their fall. Also, almost any flyer could essentially "hover" with minimal effort. Would allow for Tether salesmen, weight belt salesmen or other such.

You could combine that with a floating, upside down city that has exact opposite gravity with same issues. At the midpoint gravitational effects would cancel and there would be a dead zone that traps thing entering it without sufficient momentum to pass through.

So, what made the city stop? Does everything else continue flying up? If so, what made the city stop and anchor at some point.

Also, if you have reverse gravity it would wreak havoc on anything flying. Think about it. A bird flies by having wings that give lift and thrust. So, what happens if a birds wings give lift with reverse gravity? It would be like a bird pushing DOWN under normal gravity - it would push the creature down. Normal flight would push a flier UP at the same time that it is trying to fall UP. To actually fly under reverse gravity, a bird (or dragon) would literally have to fly upside down. That might look a bit weird. Fliers would have some serious adjustment time when they first enter such a zone.

If gravity has returned to normal, well now you need a reason for the city to stay where it was.

The floating ruin is a separate scenario from the reversed gravity idea. It isn't that the city stopped floating, it was lifted and flipped by a powerful mage and left hanging there, and no one has ever been able to figure out how he did it to be able to undo it.