Dim illumination, strobes, or flickering lights make it difficult to track movement and see clearly.
Environmental Tilt
Effect: Affected characters suffer a –2 penalty to visual-based Perception rolls, including ranged combat, rising to –3 at medium range and –4 at long range.
Causing the Tilt: This Tilt applies to scenes of “natural” darkness with dim ambient light, such as the outdoors at night away from urban light pollution, and to disconcerting environments like a nightclub with its effects system on.
Ending the Tilt: Bring, find, or create a light source.