About the Fire effect
Fire builds flames from two waves: a sine across the screen and a cosine down it, both moving quickly over time. Their sum is multiplied by how close each cell is to the bottom of the screen, so intensity is highest at the base and dies away toward the top. The intensity picks a character from a twelve-step ramp ( .,:;ox%#*+@ ), so the base of the fire is a dense wall of symbols and the tips break up into sparse dots that flicker in and out. The flames lick upward in irregular tongues rather than a uniform bar, giving a convincing campfire at any screen size. Amber and red are the natural choices, but a green or cyan fire looks suitably supernatural. Use it as a cosy fireplace on a TV, a dramatic intro for a game stream, or crop the PNG for a burning banner.