[color:"orange"]There is no excuse, ever, in any situation whatever, against any monster whatever, for any combat to be required to be fatal.[/color]

I don't see that it makes much difference to gameplay if fights end with death or unconsciousness. There have been games where party members fell unconscious if their hit points fell too low, and the party was defeated if everyone became unconscious. I think this was mostly implemented as an alternative to resurrecting dead party members, though.

Depending on how it is implemented, exclusive non-fatal combat could be seen as an attempt to dumb down the game or target it to young children, which could negatively effect reviews of the game.

[color:"orange"]It is possible to make it so that it's reasonable that you need to only kill or be killed. A crystal monster in an inescapable arena, that can't talk, doesn't breathe knockout gasses, poisoned darts bounce off, and blunt "concussing" weapons shatter it.[/color]

How about conscription and then being dropped in the middle of any war zone? Sure, you might be able to convince the other side you are there against your will, assuming you get close enough to talk without being killed, and they can understand you, and they believe you, and assuming your side doesn't see you and brand you as either a coward or a deserter. In a one on one encounter with an enemy, you might just both withdraw, if there are more you would at best likely end up as a prisoner, which probably wouldn't be very pleasant, and definitely wouldn't make for a good game.

[color:"orange"]Worse than that, it's a FPS.[/color]

Well, we certainly wouldn't want that. I'd rather combat be eliminated completely, and have an adventure game with RPG elements. Actually, I'd buy an adventure game set in Rivellon (same world as DD), Nemisis (BD) or whatever locations Larian has expanded to in the next gen game (AFAIK back in Rivellon, but we will see more areas, or just different ones).

[color:"orange"]No idea if the DD engine has anything relating to NPC interactions with eachother[/color]

NPCs can wander around, and some can change based one certain quests or triggers, but they usually do not independently interact with each other. You can (rarely) get enemies wandering too near to friendly NPCs in a couple of areas and attacking them (important NPCs are protected from dying, though), but NPCs do not steal from each other, pick up anything you have dropped, etc.

[color:"orange"]1 "Hey, I'm on your side!/I see wut u did there!" - verbal acknowledgement of wrongdoing and a warning. Important first step in escalating hostilities... or in changing people's behaviour so that they don't need to escalate.[/color]

In DD there was a particular grumpy entity which would challenge you if approached. By picking the right conversation options, you could safely approach twice (there are a couple quest items near it, if you have gotten those quests), after which it will simply turn hostile if you got too close.

[color:"orange"]3 *BITCHSLAP* Yeah. You know you want to slap that annoying fan.[/color]

This would get used a lot with one particular spoiled brat in DD, who is otherwise protected from any form of direct or indirect attack.

[color:"orange"]In human interaction, we have many social tools to prevent violence, and one of those is violence escalation levels.[/color]

Unfortunately, these levels don't seem to be terribly effective sometimes. Placed in a game and widely implemented, they could make combat realistic enough not to be fun anymore.

[color:"orange"]Even in murders, it is very rare indeed for someone to switch straight from normal to a murderous rage[/color]

Vampires or zombies don't need a murderous rage, they just need to be hungry. Soldiers in a war just need to do what they were trained to do.

Part of the appeal of RPG games is collecting and upgrading equipment, particularly with action RPG games, where that may be the main focus. Getting rid of combat, or mostly replacing it with conversations, will eliminate or greatly reduce this aspect. There was a time when every RPG game was compared to Diablo, and faulted if it didn't have a similar 'collect better equipment so you can kill stronger monsters so you can collect better equipment' model. I don't know about current games in development, but there have been RPG games that were dumbed down and made more combat focused at the insistence of the publishers, because that is where the larger market was (and perhaps still is). Even with at least some movement away from simple action RPGs, I don't see much market for a generalized non-fatal combat scheme.

Alrik has also questioned the necessity of violence in RPGs, here and in other forums (IIRC he posted a couple links in the RPG Snippets topic).