Ascension is a NFO DIZ ASC viewer for OS X, focused on being a lightweight tool with an essential feature set. It comes with full Retina support, including a Retina optimized interface and even renders ASCII art in high DPI.
You want it all? Check out our flagship app ESCAPES, where a considerably improved variant of Ascension is built-in. While Ascension is purism, ESCAPES is the candy.