The Apple ][ program was written in AppleSoft BASIC, and consisted of a series of HPLOTS -- "hi-res" lines, drawn on a coordinate plane.
The CANDLE ][ app attempts to reproduce the look and feel of the CANDLE program as it would have been rendered on Apple ][ displays of the time, with options to render as if displayed on a green-screen or amber color display, or, as the program might have appeared when displayed on a color monitor, with a simulation of the NTSC artifacts which might have caused some of what would have been intended to be vertical white lines to be variously visibly tinged with the colors green and purple.