So at the beginning of the game, a boss spawns blocking your way back. Great.

So I came back a little later... and the boss is gone. I'm assuming this is permanent and I missed out on the boss forever and ever...?

I haven't touched Valdis Story in a while (which reminds me, this game is great and I need to replay it ASAP), but if I recall correctly, yes, that boss is a timed-event. If you leave him be and reach a certain point in the game, he'll plain and simply disappear. I'm sorry if I can't be of more help, I'll go replay the game in order to give you a more in-depth answer... I know I missed fighting him on my first playthrough because I went too far in the game and he vanished, but it is most definitely possible to fight him.

Argh, so I killed Magnus, but I'm talking about what is apparently Yeti. So there is NO way to get him back?

I really wish there had been some kind of warning or notification. I tried a hack that reset the total time that I've played the game, as I read somewhere that he vanishes after 2 hours of play, but it seems that he did not reappear. Lovely.

Edit: Marked Nirth as solution because first in row. Thanks guys.


Double edit: He shows up later. How the heck do you get an S rank on anything? I am awful at this. Finished the game with an A adventure and B combat.

I think I got worse at that and I have a natural talent for these games (used to at least). They have some serious talks over Steam Discussions regarding tactics and strategy but the amount of timing and precision just kills it for me. S rank stands for Sanity, it tests it well.