I agree. Changing healing and dying is probably the easiest way to screw up the game, and I will probably change those rules both once and twice before I'm satisfied.I'm a little scared to add too much difficulty to the dying process, since damage rolls are often high.
The first thing I tried was a rule so that instant death was at ½ max hp, but that makes the game too deadly at lower levels. Especially if I won't let the characters begin with max hp at level 1.
The second try was instant death at max hp, up to your CON, then it stopped until max hp was 2*CON, then it continued at ½ max hp.
It solved the problem with the first try, but I think it's too complicated.
The third try was an instant death save with the DC equal to the remaining damage, but that was too deadly.
The fourth try was the one I posted and I agree that it's still quite deadly.
Maybe I can come up with a fifth solution, or maybe I'll go back the second solution. But I can assure you that I won't use the Instant death rule as written in PHB.

Actually in ADnD you died at -1 hp, with an optional rule that you died at -4 hp. If your character was brought to zero or less and didn't die outright he started to bleed to death and died at -10.Fuindordm said:In AD&D characters went below zero often but rarely below -10 in a single hit.
Even in ADnD2 you died at -1 hp, with an optional rule (that become default in DnD3) that you didn't die until you reached -10 hp.
In Rules Cyclopedia you died at zero hp, but with the optional rule that characters brought to zero or less hp had to make a death save every round or die, until helped.
If a character was brought to zero or less hp and survived in ADnD he was first unconscius for 1d6 * 10 minutes, then he was hospitalized for at least a week. Not even cure spells, except for heal, could change this.Fuindordm said:I like introducing a level of exhaustion or some other penalty to characters that get taken down, though.
I think that we are quite nice if we only give the poor bastard at zero hp a level of exhaustion.

OK, then I try a fifth time:Fuindordm said:I really like the Schroedinger's Cat approach!
If you are brought to exactly zero hp (no damage remaining) you are only unconscious.
If there are any damage points remaining you are dying.
Instant death as per my second try: you die if remaining damage is equal or more than max hp, up to CON, then ½ max hp then more than 2*CON.
If someone give you first aid after you become unconscious, but before your next turn, you survive.
Otherwise you must make ONE death save to survive when you get help: the DC is 1 the first round and increasing by 2 each following round up to a maximum of DC 9 at the fifth round and after.
If you take more damage that isn't instant death treat it as an extra round.
The reasoning is that if you wait with death saves until you get help it's easier to just roll one save, than to roll up to five in a row.
There can never be more than five saves, as by then you either made three saves or failed three.
And the mathematical chance to survive unaided is a little better than 55 % (DC 10), that's why a max DC of 9.
If you don't like the DC-sequence 1, 3, 5, 7, 9, you could use:
Round 1 and 2: no save (you survive automatically).
Round 3: DC 3
Round 4: DC 6
Round 5 and later: DC 9
as this is closer to the math in DnD5.
Nope.Fuindordm said:Learning spells: DC 15 is pretty hard. Would you let them add their proficiency bonus?
Someone else suggested DC 10 for learning spells, but as I understod that was for a one time roll (as in ADnD). When you have failed you can never learn that spell).
My aproach is a little more forgiving, letting characters reroll when they level up. To compensate for this softness I raise the DC.

If you don't allow rerolls you are only allowed a reroll if you fail for all spells and you still don't have your minimun number of spells that is 4 + 2 * level for a wizard.
You could lower the DC but only allow reroll when the wizards INT increases, that was the original rule in ADnD. It wasn't until ADnD2 that you were allowed to reroll at every level.