Re: A simple and elegant PbP game...
A lot depends on what you're willing to write for, Keylo. If you're not willing to describe someone's guts getting pulled out, perhaps violence should be kept to a minimum. If seeing characters waddle about, dropping eggs as they go, squicks you out, then pregnancy should likewise not be a significant factor.
I'm fine with writing for most things, at least the ones you mentioned here. What I'm "not" sure I can exactly write for, is probably futas as I personally dislike the fetish... But that's not a major concern, mainly as I could just treat it as if I was writing "male" on "female" instead.
Given this board's proclivities, I'd say impregnation and rape should both be in the game. I wouldn't want to permanently retire characters, unless you're willing to provide a mechanism by which a player can start a new character and catch up (taking AWMBI as an example, if characters disappeared permanently, it wouldn't be hard to add new characters as they don't actually level up very fast).
Probably not going to permanently retire characters after some input from RJ in a discussion about this, and the points you provided here. What I "may" do instead, when a character is raped to oblivion, is most likely a "purity" system, similar to the "mental"/"essence" system in AWMBI. Current version of the purity system causes the character to temporarily go into a sexual frenzy upon full depletion of purity for the rest of the encounter (or in short, turn around and rape their friends) without receiving "purity" back via teammate support skills. Of course, being knocked out regularly will still exist as well, similar to AWMBI.
I'd say make it four "base" stats, and then some "derived" stats. Like HP is based on STR, and MP is based on WIL, and then you have AGI and PERC. Or something. What stats you have depends on what kind of actions you can perform.
Current design, for a four "base" stat system is: Power, Dexterity, Mind, and Endurance. Power is mainly melee damage, sub base for "stamina" and "agility" in that it also refers to how much reserve energy a person has, etc. Dexterity is basically the main stat for aiming, agility actions, etc, and for now, is the "main base" for many types of actions, but the sub base for none. Mind on the other hand, is the main stat for "magic" attacks, as well as things such as perception, things requiring memorization or intelligence, and so forth. Mind also plays a role in assisting as a sub base for things such as aimed attacks, dodging, purity, etc. Endurance, as the name implies, is the base stat for stamina and purity, and is... basically that.
I'd also say both impregnation and rape should have lasting effects. Impregnation would leave your heroine with some piece of monster flesh leeching off her, so a penalty to agility. Rape would be more of a mental effect, penalizing willpower as the girl tries to cope with the memory of being raped.
For now, impregnation is a... ehh...thing, usually taken care of at the "Safe Haven" for now, but it may "actually" become a downside in that it drains purity and may create another enemy for the PCs to fight depending on what I decide to do. Rape however, is a definite drain of purity, and will probably be tied in with a tad of stamina damage as well. These are just ideas for now though, so nothing's really finalized in this area.