Re: The Flesh Cavern
Glad you asked! The four different characters have different strengths and weaknesses, as mentioned. The barbarian, for example, has the highest starting strength, allowing her to move heavy obstacles such as debris. The thief has high agility, which as well as having a hand in dodging and hitting attacks also governs lockpicking to open doors and chests. The magic user is able to see through illusions, revealing hidden doors and rooms, and she's also the first character able to activate portals; which once activated from both ends act as shortcuts between two areas. The merchant is a balanced character who starts off able to do middle ground checks; moving smaller debris which the magic user would be unable to, or activating the weaker portals which the barbarian can't do. She also gets a discount when dealing with merchant npcs. However, while she can do a lot, she suffers from a slightly higher minimum lust and is a definite jack-of-all-trades; master of none. Speaking of lust, the health parameters are HP, Energy, and Lust. Energy is used for special moves, whereas if HP is depleted or Lust maxed, the character is defeated.
In addition to this, all characters have their own separate exp, levels, and inventory. This is to encourage the player to switch between characters often; to further incentivize this, the easiest way to restore HP is to retire for the night, which health potions and the like being expensive and/or rare. And, of course, if you only use one character, chances are they're eventually going to get captured, leaving you with a choice of weak characters to try and rescue them.
All characters have unique scenes for each enemy and capture scenario, as well as unique bad ends for each scenario. A short scene will play each night that passes when the player retires the remaining characters for the day for every character that is captured, reminding you of their plight and giving you clues as to their location. So if nothing else, playing other characters allows you to see different takes on scenes. And rather than it being variations, each scene is written from the ground up. Even in the case of similar situations, they're still done from scratch, not rewritten.
We'll see how this is received; well, I hope! However, once I have the core details in place, I'm going to see about adding an 'easy mode' which gives a bit of exp to all characters, like using an exp share in the new pokémon titles. This will have other advantages, too; one idea I'm toying around with is that Boss enemies heal per day rather than starting at full hp again the next time you fight them, allowing you corpse run a troublesome boss by just suiciding against them. Easy mode would nerf or even remove that healing entirely. HOWEVER, that would likely not be in the initial demo, and is, for now, an idea.
As for your other question, I am all about source, but I'm afraid I don't understand what you mean. If you would prefer to keep it private, PM me with an elaboration. (I may not respond tonight as I'm about to head to bed.)
Edit: Wait, I'm just very tired and misread your question. So you want to port it into a different engine, or something you've made yourself? That's totally fine; just drop me original credit. A link to my blog would be much appreciated as well. I would be interested in knowing more before you do so, however; PM me.