You enter that ring and Stealth check against Passive Perception is required.
Not so long ago i had the same idea ... even remember suggesting something like that.
Now i wonder if it wouldnt just add another space players would walk on the edge being perfectly undetectable. Imean 2,5m seems short ... especialy in PC game where that means that 2,51m you are perfectly fine in fullplate and no dexterity at all.
Im not sure if this wouldnt overcomplicate things unnecessarily ... But i would preffer noise ring around character ... and hearing ring around NPC ... wich would also give some easy stealth check if one goes over another ...
You get me right? Like even if you are quite far ... something can go wrong.
My suggestion is for 2 hearing rings. 1 is 2.5 meters radius around the target. The second is between 2.5 and 5 meters. And that is with Wisdom 10. Wisdom 15 would be 15 feet radius or roughly what... 4.5 meters, and the second ring would be roughly 4.5 to 9. The idea is that players would have to make 2 checks, 1 for each ring, to try to sneak up on someone.
Also, remove the ability for players to see sight cones and hearing rings. Then you have no idea if you are in a ring or cone or not. It's hard to exploit the system if you can't see the cones and rings.
But I'd actually be totally happy if they just removed our ability to see the cones.
