Obscured - caraminden/anathema-roguelike GitHub Wiki

A character is considered Obscured from the perspective of an enemy if the product of the Opacity of all of the Locations in the straight line path to the enemy is greater than or equal to 40%. While this can get a bit complicated with Gases, in practice this means that there need to be 2 Low Opacity Locations between a character and its enemy, or one Medium Opacity Location in order for the character to be Obscured from the perspective of that particular enemy.

If a character is considered Obscured from the perspective of an enemy, that enemy treats the character as though it had one level lower Visibility than it would otherwise.