Hey sorry for the super-slow response here!
I wrote an image-to-ASCII converter for the email profile-pictures, since this seemed like a fun way to author them (I'm no good at ASCII art or illustration, so it seemed kinda enjoyable to draw some bad pictures and auto-convert them to text characters, since that conversion process gives them a sorta distinct and unified feel even though I'm not able to create a good+distinct aesthetic by hand). This basically amounts to splitting the source image into a grid (each grid cell contains some rectangle of source-pixels and corresponds to one ASCII glyph in the output), and then looking through the list of all available ASCII glyphs and seeing which one's shape matches the source pixels inside that rectangle most closely. The game's title card is using that same conversion system, just with a much larger image!