Homestuck was popular because it was the biggest CYOA at a time when 4chan Quests were a major mainstream meme. It wasn't one, it was scripted, but it was piggybacking off Problem Sleuth which was his previous (actual) CYOA. It has the same tone and "quirky" visuals as Undertale and could be considered proto-Undertale. The difference is it went on insanely long and was insanely complicated to keep people invested, like a soap opera.