MONSTER REVIEW INCOMING!
Loved this game. I played it longer than any other LD this contest, probably about 5 hours. What really stands out for me is the trick--which is a wonderful idea (though I think it will not play out well with the LD audience just because of the format of the contest)--and the thoughtful level design. The music is great for setting the mood; I can't believe a 45-second loop was listenable for that long.
Remainder of review contains spoilers:
I got all of the endings except the egg one, without spoilers or cheating (though without your hints in the comment I certainly would not have noticed that the game is different for each computer that loads it). It was fun to explore the cave, but I definitely needed to draw a map:
http://discovery.spacebar.org/dry-voices.jpg
I believe the underlying idea is very very good. You could make an outstanding and large game this way. There were some problems, though: First, even when you kind of figure out what's going on, it's still troubling because there is no confirmation in the game. I had figured out that there was some cookie-based state, and that some of it I could influence, and that some of it was outside my control (but if I kept reloading in incognito mode it would sometimes change). But I can't see the state without exploring the places in the game, which takes some time, and I don't know if my next step is to reload to try to initiate some new state or to explore further. (There are various jumps that are almost makable, that lead to invisible corridors, for example.) Ideally, once I've figured out the trick, the game would give me some indications as to what's been discovered in this particular session, or let me choose starting items, or something like that.
I must admit I was led quite astray by the asterisks in the ending messages and your hint in comments. I was initially convinced that the asterisks were some kind of clue themselves about letters that needed to be anagrammed (because of hint in URL) to spell a name, once I got all of the endings.
Another thing I thought I was discovering (but I don't think it's true) is that there is a single timeline, with each of the named characters existing at a certain point in time, with their actions having effects on the cave for later players. The thing that's random about the stranger is WHEN he visits the cave (between named characters), not anything else. That would have been great because the player could bound the randomly generated state to the number of named characters + 1. Kind makes me want to make a game like that. I had some other theories that turned out to be so off-base that I will save them for possible use in my own future LD entries. :)
When I got really deep into the game, there are some disappointments. For example, the key is not necessary. Why isn't sisi's note up in his loft, behind the door? Why does K7 exist at all? Ron's lower jump should allow him to make it to a place where the other characters can't reach, but there doesn't seem to be any. There should be a reward for taking the long way left (sans sword), but you can get equivalent endings by exiting to the top right or just being born without a sword available. Music fades out near the edges but is always the same; why? Some bugs too: If you move quickly between rooms, the screen blanks out and you're done for. Gana can hurt herself with fire at the edges of rooms, even killing herself, a case which doesn't seem to be handled by the code. You can step on the top corners of gates and sometimes onto smooth walls in the first row or two of tiles.
The cruelest part of this game in its current form is the boot, though. There are loads of things that telegraph the importance of the boot: You're likely to see it on your first playthrough with the sword, or almost certainly as ron, it sticking in your mind then as you explore. The endings all say, "... especially in another's shoes." There are several unreachable and unseeable areas that are upward (like in Sisi's place, but also to the left of Gana's home, and a few rooms up from the start), especially right above the boot itself. These lead me to believe that if I get the boot with the right character, I'll be able to jump higher (or learn its owner's name, who can jump high) and explore these places. The boot is locked on both sides from players who can't attack, so I was pretty convinced that it would be Sisi, who is looking for "something amazing." Moreover, the map for Sisi tends to guide you out to the left, unless you really know what you're doing. So I'm thinking that if I can get either Ron or the stranger with the sword drop to leave it somewhere (telegraphed by the fact that there's a body where the sword would normally be), then I can get the sword with Sisi and discover the boot. I spent a while on this, but I wanted to leave my comments for this game before the rating period was over, so I spoiled it for myself by looking through the source. Red herring boot?! ffffffuuuuu... (Too bad, because I probably would have found the egg if I hadn't been distracted by that thing.) That said, I think you actually did have something like this in mind, because it's hard to explain the level design without it. So I am quite sympathetic to running out of time in LD, especially since this game hangs together really well even as is.
Summary: Great idea and execution, which really grabbed me but is unlikely to grab the LD audience because of the format and presentation, so I think this game will be underrated. Easily expandable to a large and ambitious game. In any case, I see you're quite young and have great game sense, so please carry on as you see fit!