We have a
thread which is about guessing music from adventure games, and a year or so ago I made a big file for that thread using only classical music from adventure soundtracks. The two instances of the Dies Irae that you mention were part of it. In fact, it was hearing it used ad nauseam in Might & Magic: Clash of Heroes (see
here, e.g. at 16:00) that made me think about its use in adventures, which in turn prompted me to look for more classical music in adventure games. It's nice to see I'm not the only who's been wondering about its use in games.
Anyway, at the time I tried to think about more instances of the Dies Irae in adventure games and couldn't think of any.
(And so that post is not much help to you. Sorry!)