I have long liked the idea of a “new characters always start at 1st level” house rule, but due to its obvious extreme harshness have never been bold enough to actually implement it.
I did it for my last (three year) old school game. As folks have noted, it works in part because the advancement tables are geometric, so with even division of XP, by the time the survivors have gained ONE more level (and assuming they haven't died or run into level drain), the newbie is only one level behind.
Level drain, item destruction on failed save, and system shock-resurrection checks are all in my game, but not as house rules: they came in the tin with the rest of the game.
Level drain and item destruction are great, as is save or die poison, but I like to signpost energy drain and poison, and to make mitigating effects relatively common. And finding new items. Losing stuff, levels, and dying like this are easier to take and more fun if gaining levels, new stuff, and finding anti-venom or resurrection magic are also easy.
Probably the harshest actual house rule I have is that I make casters roll to aim or place their AoE spells;
I introduced minor scatter rules for AoEs in my last 5E game. Fireball was getting a little monotonous with the precision placement in melee.
Level Drain (or any other effect that decreases an ability score) because it's a PITA to have to recalculate all your stats because your modifier changed. It's one thing to do it at level up because those are permanent changes, not temporary adjustments.
I like 3E's innovation of negative energy levels. Each level drained = -1 to hit, save, and skill checks, -5 off max HP, and lose your top level currently available spell slot. After 24 hours you get a save for each NEL for it to either wear off or become an actual lost level. That way the mid-combat math is simple.
But I remember in 1st edition days puzzling through the rules looking in vein for the “critical hit double damage” rule.
In 1E instead you have Gygax specifically inveighing against critical hits:
"As has been detailed, hit points are not actually a measure of physical damage, by and large, as far as characters (and some other creatures as well) are concerned. Therefore, the location of hits and the type of damage caused are not germane to them. While this is not true with respect to most monsters, it is neither necessary nor particularly useful. Lest some purist immediately object, consider the many charts and tables necessary to handle this sort of detail, and then think about how area effect spells would work. In like manner, consider all of the nasty things which face adventurers as the rules stand. Are crippling disabilities and yet more ways to meet instant death desirable in an open-ended, episodic game where participants seek to identify with lovingly detailed and developed player-character personae? Not likely! Certain death is as undesirable as a give-away campaign. Combat is a common pursuit in the vast majority of adventures, and the participants in the campaign deserve a chance to exercise intelligent choice during such confrontations. As hit points dwindle they can opt to break off the encounter and attempt to flee. With complex combat systems which stress so-called realism and feature hit location, special damage, and so on, either this option is severely limited or the rules are highly slanted towards favoring the player characters at the expense of their opponents. (Such rules as double damage and critical hits must cut both ways ~ in which case the life expectancy of player characters will be shortened considerably - or the monsters are being grossly misrepresented and unfairly treated by the system. I am certain you can think of many other such rules."
I've been in games and run them where the DM tracks HP for the PCs. The game was basically set so you were:
Healthy = 76-100%
Injured = 51-75%
Wounded = 26-50%
Maimed = 1-25%
We used to track our own HP but use those categories (well, similar, Scratched, Wounded, Badly Wounded, Near Death) for communicating to other PCs. We didn't allow telling other players your exact HP.
I'm sure you could. It just comes down to I don't have the desire to comb through the editions to decide what I like and what I don't and then combine them into a single cohesive system.
This is one plus side of the plentiful retro-clones and variants nowadays. You can almost always find one that's a good fit.
It is perfectly reasonable IMO for something like a troll's issue with fire, or lycanthropes and silvered weapons, to be "common" knowledge in a fantasy world. However, such knowledge should not be perfect or always just assumed. For example, silvered weapons with werewolves might be distorted in the telling to include holy water--"Don't you know you need a silvered weapon, dipped in holy water, and blessed by a priest!"--instead of just, "No, a silvered weapon alone would do it... I don't know where you got the rest of that from."
Not every PC will know the "truth" or facts when it comes to such things. Some might not know them at all, others have it incorrect, and other know the truth of it. That is what I am talking about and why a simple DC 10 Intelligence check suffices in most cases IME.
Without this, how do you know what "real world" knowledge a PC has in their own world. I mean, the characters live IN their world, they should know certain things, right??
Now, what you thought I meant is very annoying and frustrating, I agree. And I don't jive for that, either. If a player can't remember details, write them down, otherwise your PC is going to embarrass themselves when the call the town "Merrydown" when it fact is was "Thusselton" or something.
Agreed. I do like to re-skin monsters so I rarely have to worry about or police inappropriate character use of player knowledge.