first off: loved the game, but explaining what I loved (and the few things I disliked) would take too long here, since my following theory is already fking long enough
now, secondly: *SPOILER WARNING FOR THIS GAME AND ETERNUM*
I have a little theory: once in a lifetime and eternum might take place in the same universe. this is of course supported by the little teasers for eternum in this game: judie and lauren talking about the upcoming release of eternum, the secret no-girl-path ending and, for my theory most importantly, the prison ending. now, what if this ending was actually the canon ending of the game. I know, very depressing thought, but it would tie in pretty nicely into eternum, since astaroth tells us to help him with calypso. quote: "calypso, [name]. that is the only thing that could become a hindrance to my plans." This is all just speculation, but I think astaroth might actually be thanatos in eternum. for one, their names are almost anagrams of each other, only replacing an "r" with an "n". also astaroth's goal seemes to be some sort of world domination or something similiar, so trying to find all the gems of doom to become the new head of the most powerful company in the world (like thanatos seems to do) would definetly be in line with that goal. anyway, thanks for reading my ramblings, I know this is isn't really a strong theory supported by a lot of evidence or anything (and all references to eternum were most likely meant as advertisement), but I would lose my mind (in the best way possible) if this ended up being anywhere close to true.