The kind of vegation that is at least waist high.
Visually as you walk, you can see your self and anyone else walking (running)
{Nothing different here}
If you squat, you can only see the top of their head (or your head and a ring around you). You could still see others who are squating or walking/standing.
{Just more difficult to see visually others. Possibly targeting modifiers}
If you go flat (crawl/prone) you can only see your ring of your location.
{See, see who. You could only see someone one with in your perception range in feet/meters/or some other limition. Of course area effect weapons could still hit you if you are near them. And if the wheat/grass is dry, burning it to flush you out is an option.}
I don't know if this has been done in anyother MMO. I know that in some games that you can walk into water and other low places and it makes you hard to see if playing first person. But I was thinking the classic Fallout view point.
Dave Chase