About the Pulse effect
Pulse draws a single ring centred on the screen whose radius breathes in and out on a sine wave. The ring is rendered with the shading blocks ░ ▒ ▓ █: cells right on the ring get the densest block, and cells a few characters away fade through the lighter shades, giving the edge a soft, glowing falloff. As the radius shrinks to zero the ring collapses into the centre, then blooms outward again until it nearly reaches the edges of the screen, which reads like a radar ping, a heartbeat or a speaker cone. The motion is slow and symmetrical, so it frames centred content well: place a logo or countdown in the middle and let the ring pulse around it. Red or pink suits a heartbeat theme, green a radar screen. Raise the speed for a more urgent alert feel.