I wonder if it would have worked better if it just ended without the "To Be Continued"? For me when I saw the end I just thought "Oh, so we'll see what happens in the sequel" rather than "Oh god oh god oh god oh god what's going to happen to my Naija? 
". I don't know a lick about story telling or game making, but I can't help but wonder if I would have gotten that feeling from a textless ending.
Yes, I'm aware that this is kind of an old post, but the forum doesn't seem to move very fast so I hope it's OK if I respond to it.
For me, this is more or less the case - I'd have been much, much happier with a self-contained story which didn't end on a veritable cliffhanger. Sure, leaving the door open for a sequel is never a bad idea in case you decide to make one (as there are few things worse than cramming in a sequel to a game that didn't leave room for one), but I feel it takes a lot out of a story if you end a game on a "To be continued..." in all but a direct statement to that effect, especially when you're not sure if you'll actually make a sequel that concludes the story. It leaves the narrative without a solid sense of closure, and while it does build up enthusiasm for the next game in the series, it hurts when there is no next game at all. To draw a parallel, I loved Advent Rising and I loved the story it told, but the game seems to have bombed on the market, so the creators lost the rights and the story is left hanging with "There is still so much more to tell." Well, there is if you actually tell it.
That's not to say I dislike Aquaria. Far from it. This is still one of my all-time favourite games, easily blowing AAA 50 Euro titles out of the water (if you'll pardon the pun) easily. To this day, Aquaria has by far the best atmosphere out of any game I've played, and that's across the board of themes, from aerie serenity to light-hearted jubilation to heart-pounding action to blood-curdling horror and beyond. In fact, for a game that's this light on narrative and features predominantly a single character and a single voice, what's accomplished by atmosphere, MUSIC and the few but well-placed lines trumps Hollywood's fat wordy dramas every day. And the ending isn't a let-down - far from it, it is a major high-point... For gameplay that doesn't come. Were this a plot point in the middle of the game, I would have been so excited to keep playing and find out what happens afterwards. As it is, it gets me excited for nothing, and that kind of sours the mood right at the end.
It's true that we're usually sad to see most amazing adventures end, and it's normal that we'd want to delay that end and prolong the adventure. But a good climax to a good story should make us WANT to see it end, not because we want it to be over, but rather because we care about the resolution more than we care about the status quo. To that effect, if the game had simply ended with: "And we lived happily ever after. Well, until our next adventure began, but that's another story for another time" I would have quite literally no complaints about Aquaria. It would have left the door wide open for a sequel and gotten me interested in seeing it, but it wouldn't have taken away from everything that was achieved in the story. And right now, it kind of does.
And, yes, I'm ever so slightly invested in the game's story
Every time I replay Aquaria, I'm reminded of all the things I liked about it, and all the things it has inspired me to write. It's a good story, and I would have liked for it to have been given a conclusive ending.
