Armadimmer 

a screen dimmer 

This utility is designed for users who work across multiple displays. It allows for precise control over the brightness of entire screens, reducing peripheral glare and helping you maintain focus on your primary task.

Special effects are included as well, such as:

RED SHIFT: A true red-filter for windows

VIG: Vignette mode
CYB: Cyberpunk/CRT Effect
PSX: Dithered pixelated dimming