I was actually thinking about about making him into a playable character in my fan-game...But that would require even more work and fleshing out of the storyline...I actually have three alternate endings planned: sad, normal and a perfect ending...

With regard to Zio as a playable char, well, I would need some feedback from the fans, obviously, and see how they feel about kicking out Rune and replacing him with Zio...By kicking out I don't mean bumping off Mr.Walsh, he is, after all, my favourite character after Alys.
But you can post your ideas in my game thread/post.