Picked this up once a couple years ago. The part of Zellen first appearing was the end at the time.
Came back now and, after doing a slow crawl to the ending, did a mad dash through every decision possible.
After getting the "true ending" the first time, I thought it was a joke, or a secret ending done by making a specific, unlikely set of decisions. Mostly because the true ending...feels like a joke.
The game had me in the first half. But unfortunately, after that the variety peters out, and almost regardless of what choices you've made, the two endings are basically "You did it! Here's a silly ending cutscene", and "You didn't it! Here's a silly ending cutscene!"
Even the mild bit of mystery the story presents not long before the ending just kind of...gets resolved immediately and effortlessly, and then suddenly the game ends.