What secret ending? I messed up the romance story line of the teach and Judie, so maybe I didn't get the perfect ending. I was being too nice and the game assumed I didn't want to date them. By the time I saw I was locked out, it was too late. And I only had one save file.
If the MC of OIAL is the same as Eternum's, I can buy that secret ending idea that both games are just servers in the same giant MMO. But I still think OIAL happened. The book didn't help the cult take over. And the cult is reffed (referenced) in the game, Eternum (with a newpaper and some dialogue). I think Eternum is just another cult's way of taking over since witchcraft and cloak and dagger stuff didnt' work.
President Stabb is I think still president, but I only here about him when the MC is at school or around town. But I wouldn't be surprised if he is play Eternum. In this game Chang and Chop-Chop seem to be the "Stabby Mike" character. So i'm doubting Stabby shows up.
I think both games exists too. But I think OIAL ends where Eternum begins and Eternum is a lingering problem from the time in OIAL. Something the MC didn't notice that was allowed to thrive.