One of my favourite R18 games and perhaps one of the greatest pieces of the genre. I finished the game several months ago, realized today I had not rated it and considered not doing it a disservice to one of the best games in this page.
The story is fascinatingly interesting, mixes occult and fantastic elements masterfully with the pretty realistic setting and every single plotline, even the pseudo-tangential ones (Jasmine's romance line, for example), are developed and finished pretty much flawlessly. On the same line, the characters are all charming, interesting, deep and/or funny as fuck, normally all 4 combined; and all of their development makes sense and is very well written.
On top of that the comedy is absolutely genious. While humor is usually a very subjective matter in story driven games (be it pornographic or not), in this specific case not one joke went unnoticed or without getting at least an exhale of air through my nose out of me. Not that it couldn't make me laugh: This is, while not the only porn game that has gotten me to laugh out loud, the only one that has gotten me to laugh to the point of having to muffle it to not wake anyone up in my building. It is to the point that I genuinely think I would get along with the creator irl just because of how well their sense of humor hits me.
The artwork too is really, really good. Caribdis has a unique aesthetic I have not seen before; one that is both unique and different enough to be a nice change of pace from the copypasted 3DCG models most games use, and not so far out there that only people with specific tastes could enjoy. It's cute without being too cartoony and realistic without being the same 6-10 models that repeat themselves in pretty much 90% of erotic 3D games.
With all of the above, I would have played and enjoyed this game even if it didn't have porn; but even that is excellent: While the animations start somewhat clunky and average at the beginning of the game, by the midpoint they are already more than decent, and by the end it looks like what an experienced porn games dev would make. The improvement between the first few animations and the last ones is impressive to say the least.
Finally, in terms of choices and mechanics, even if there's nothing special, the game does nothing wrong either: The choices are divergent enough; even if they mostly revolve exclusively around gaining or losing points with each of the girls, there still are a couple that give you the chance to greatly alter the ending, and even if this system isn't unique, "if it's not broken don't fix it".
In summary, this was one of the best erotic games I've ever played, with some of the best story, characters, development, humor, scenes and presentation that the genre has to offer; easily one of my top 5. With this game alone Caribdis has turned into one of my favourite developers by far, and from what I've played so far of their new game, Eternum, it seems that's not going to change any time soon. Congrats on developing and writing one of the best games to ever be in this website; I'd genuinely recommend giving Once in a Lifetime a try to any and all users of F95Zone, and to support Caribdis in any way possible so that more games of this caliber may come into existance.