So during my first play today I came across a Mythos event that said it affected the investigator with the highest observation. Problem was that two of our investigators both had an observation of 4 (the highest). I couldn't find anything in the reference book at the time but what do you do in that situation? Do you choose who it affects, or do both investigators get hit by the mythos effect?
In the interest of time since I kept going back and forth through the reference book during that moment, we opted that both of us should take the test.
Rules Reference, page 2 wrote:
During the game, some game effects may lead to conflicts within the
game or between the investigators.
* It is possible for a game effect to have more than one possible
outcome. In such a case, investigators as a group determine the
outcome of that effect.
The players, as a group, decides.