Do the opposite. When you want to remove the sight, just give all of your units (except for the unit that you want to keep sight) 'AIsi' ability with negative sight (-2000 or so) value, that should work, I think.I thought about this option but I have so many units in my map and this would mean that for any unit spawnable for any player, I'd have to go through so many units in object editor and add the ability manually (...) this seems to be a really inefficient solution.
There's one more problem: this doesn't prevent the sight granted by special sight modifiers such as Far Sight.
I mean if there is absolutely no other way.. I guess I'll just drop the idea.
That would be so much less effective then what i suggested because of all the performance wasted for iterating through all units and adding abilities. That can really slow a game down if you do it too much.Do the opposite. When you want to remove the sight, just give all of your units (except for the unit that you want to keep sight) 'AIsi' ability with negative sight (-2000 or so) value, that should work, I think.
Added the map, it happens 10 second after the game starts, you can use a timer to remove the ability later. (I didn't know how to use timers, still learning >"<)
and btw...why do you want to remove the sight of Far Sight :-ss?