If you have enough dexterity/dodge skill - you can effectively walk on the air.
Basically that’s just because ledges <> open air, but for some reason they are used for being open air.
You can also stand on nothing, similar to this: http://smf.cataclysmdda.com/index.php?topic=8449.0
I believe you only encounter this if you use the experimental z-levels mod.
It’s one of many inconsistencies that has, it’s only shipped with the game so people can have a test platform for making new multi-level buildings.
Why… Like… What. What is the logic the game has, that if you have enough dexterity you can walk on nothing?! It’s not like nothing tiles had a dexterity check.
Should require either really low or really high IN: it’s the cartoon ability to just not notice you’re no longer on solid terrain. So long as you avoid looking down and making an “uh-oh” face, you’re fine!
They in fact do require a dex check, because they’re coded as a “trap”, because they’re kind of a hack.
Dammit. That is not kind of good. Isn’t there a way to make a trap ignore Dex checks?
Seems about right, you are just dodging the Earth as it furiously attempts to charge at you, the attacks is actually very choreographed, any skilled martial artist would probably be able to dodge it.