[Joseph Jostar]

As an example: GMs can be invisible. But you can bypass this by doing the .dblclick command. It renders the whole point moot. A lot of people do this habitually now to avoid doing things that would get them banned by a GM watching to make sure they weren't doing whatever activity.

I don't really think players should be able to keep watch for GMs in such a way, when all they're doing is trying to avoid getting caught breaking the rules.

so make the proc fail if they're invisible

As a very, very simple counter to this, you shouldn't be able to see things that aren't on their icon because they're small as hell from a long distance either. Say a character has ring that proclaims their nobility and you're staring at them from across town. You aren't going to be able to see that unless you're close to them, or at the very least, you shouldn't be able to. And before you say "people wouldn't do that," I've seen it happen firsthand and have had it happen to me.

There's no good excuse for you to be able to observe people from long distance or across the whole game itself.

a modest amount of metagaming is actually helpful to roleplay, contrary to popular opinion. things like distances and measures of time should be handwaved for the sake of roleplaying rather than taken as absolute. as an example, the capital cellsvich which is home to probably hundreds of thousands of people or more has like five buildings on its town square's in-game map.