How do you Referee Darkness/Invisibility?

[graelth]

I'm looking for clever ways of refereeing an attacker who cannot be seen (whether because of darkness, invisibility, a blind opponent and so on), either a rule you use or a set of different considerations (if you do not use a "one size fits all" rule for all situations).

The latter may actually be the most interesting to me, I think, since a lot of rules just end up being a modifier to the chance to hit (which is a bit boring) or tests to detect (which is ultimately the same thing... just something that reduces the number of attacks that hit each round).

Do you, for example, let non-visible attackers always strike first? Can they be hit at all? Does attacking one randomize hits, so you might hit an adjacent ally (suspecting that the invisible opponent is between you)? Do you use a deck of cards, or a bluffing game of some sort or "I Spy with My Little Eye" (everytime they ask a question or get it wrong, the enemy attacks!), or does everyone get up out of their chairs and play a big game of Marco Polo in the house?

[sixdemonbag]

I like to steal 5E's Advantage/Disadvantage system for situations like this. But, Piper 's methods are really great too. I really like the initiative and damage bonuses! Very clever.

[howandwhy99]

Sight is a big deal in every game. When players PCs cannot interact to coordinate themselves, then they are not allowed to work together at the table. No communication means no talking at the table. No hearing means sight only at the table. No sight, as in this case, means everyone can work together, but ultimately, after all verbal (no notes or drawings) communication is finished, the players without sight each write their own action declarations separately and hand them in privately. IMC, this means no shared initiative is possible either.