Opacity - caraminden/anathema-roguelike GitHub Wiki

Opacity is a value from 0% to 100% that represents how well Light can pass through a Location, it is also important for calculating a character's Visibility.

Gases also have an Opacity value that affects the Opacity of Locations the Gas is in.

Gases increase the Opacity of the Location they are in by their Density multiplied by their own Opacity value.

Opacity Level	Opacity
No	0%
Low	25%
Medium	40%
High	60%
Full	100%