Most would like to make death a more significant event, and not just the best status condition. On this one I've some ideas already---I'm going to make the Law of Death fairly solid initially in the world before it is eroded or destroyed with these ramifications:
No undead can be made nor can the dead be raised. While the Law of Death (think Cronicles of Thomas Covenant here for flavor) is in full effect the dead are totally separated from the living and there's no traffic between them. The first resurrection in this game will be an event with very far-reaching implications, because it will also unleash the scourge of undeath on the world.
People actually die (in the sense of soul departure) at negative their total hit points. They can be magically healed as normal at any point before that. A CdG or similar effect is just an automatic crit.
I like this concept. I think death should be a little more of a serious event. But then if you make it an end of the line type thing, you have to make it really difficult to actually kill someone. I like your idea here. It makes the Assassin class, or any auto kill class, extremely dangerous; something to be truly feared.
I don't know that I would reduce CDG to a simple crit though. I mean it's probably a good idea to eliminate it as an auto kill. But IMO it also shouldn't be a standard crit either. What if a CDG to a living opponent did damage as a normal CDG but instead of auto killing them on a failed save it dropped them to 0 HP or less and they started bleeding out. (Of course if the enemy were at 1 HP then the CDG would take them to far lower than 0 HP but you get the general idea.) Then a second CDG was required to kill them completely. Just a thought.
They'd like to see a more dynastic feel and a longer scope of time than in most other games they've played. I'm thinking to further adapt a lot of the Pendragon rules on this.
I have been thinking about trying to build a very complex and in depth world for my next game. A few issues I want to put a lot of time into are:
1) Building some sort of local and broad spectrum reputation system, to include different factions (Nations). This will affect to some degree social interactions as well as buying and selling goods and services.
2) With the low amount of feats most classes get, in a highly dangerous campaign players tend to focus on combat applicable feats. This tends to leave RP feats, non combat applicable Skill feats, and Item Creation feats on the back burner, if they are ever taken at all. That is fine in a game that emphasizes combat where RP situations and Economy take a secondary, if present at all, role. But in a game where Combat, RP, Economy and a few other things all take equal precedence, that system just won't work to the Player's advantage. So my idea was, for Player Classes, to divorce RP and Economy based feats from the normal feat progression. I am not sure how well this will really work. But my base line idea was to give the PCs two feat lines. Their normal, level progression, feat line for combat applicable feats and a mirror feat line used only for things that will give them a boost in RP, Item Creation, other non-combat areas. The only hiccup I see at that point is Rogues and their Talents. With the APG they have many Talents that are strictly RP based but most would probably use all of their talent slots to make themselves more combat viable. So I might consider making an extra "half line" of talents for them to use specifically for RP based talents. So by 20th level they could have 10 regular talents and 5 RP specific talents. I haven't done any play testing for this idea, it is still in basic concept form, but I think it would make extremely well rounded characters. This also includes a slight change to the Skill system too, nothing big but perhaps a few bonus skill points devoted to Knowledge, Profession, and Craft skills, maybe a few other optional RP skills that don’t see much use in most games I have been in.
3) In depth Haggling rules for buying and selling goods and services. PC reputation and factional alliances would be a piece of this system.
4) Down time events. Item Crafting, Professions, Guild involvement, things of this nature will be present and prevalent in the game. It may in fact be important for the party to have an Item Creation capability as depending on the setting, magic items may not be widely available.
5) PrCs will get a major overhaul. They will, for the most part, be intertwined with guilds and factions. Certain guilds will offer the PCs opportunity to enter into certain PrCs. It won't just be a "I have all prerequisites and I choose to take a level in X" there will be RP events involved and there will be tests that the PCs will be forced to pass to enter. I am not a tyrant, if the player lets me know they intend to take a PrC I will direct events to allow for it. I have had large success with this type of system in the past. Instead of just gaining a level and essentially multicasting, my players truly felt like they had achieved something prestigious when they were admitted into their PrC. It did take extra time, both on my part and on the part of the player, but it was worth it. I did one on one games with them for the entrance tests and it worked out really nicely. I also considered turning PrCs into a type of template/kit added to the PCs base class, but I haven’t done any work on that at all yet, it is still just a concept floating around in my head. This would probably also involve some work gauging how accurate this keeps with the current method of judging CR levels for enemy encounters.
6) The final thing I have been putting a lot of thought into is allowing the Players to play their Characters up from children growing up in the same community: Either starting with apprentice level classes, or possibly allowing the players to start out with negative XP as NPC classes as kids and moving to their level 1 PC classes when they reach 0 XP. So they would still level up normally but would have a slight advantage with a few things. It might raise their APL by 1 or so for gauging encounter CRs. Their favored classes would still count as their level 1 PC class. The advantage here is that they would be able to play through a common background story and would have things in common with each other at the start of the campaign rather than “you all meet in a tavern” or whatever. In return they would get not only some increased comradely in their party but also a small advantage to HP, BAB, Saves, and Skills at level 1.