We've all been there. You're playing D&D and suddenly things aren't satisfying anymore. The most common culprit: hit points. Why does a healing spell heal the wizard proportionately more than the fighter? Why can high-level characters fall hundreds of feet and walk away from it? Why can my frail wizard laugh off a dozen bandits' sword blows after Random Encounter #9,870?
It's time, you think, to make D&D grittier and more realistic. It's time for...permanent injuries. You implement critical hit charts, random tables, gruesome wounds, and maiming beyond the bounds of healing magic...and nobody's having fun. The game grinds to a halt because players are either unwilling to play dashing heroes and daring adventures for fear of crippling their beloved characters, or they sulk when they do heroic-adventurey-things and their characters are permanently scarred from it.
How to fix this?
GM Thom is here with some advice.
Stop Playing D&D
Yep. That's the ticket. D&D is not a game designed to handle permanent injuries. The premise of modern D&D is heroic fantasy. Players create adventurers in a relatively complex character creation process that creates an inherent attachment. It's not 3d6 down the line, name your wizard Male Elf, and pray you make it out of the dungeon with enough treasure to hit level 2. Those days are gone, unless you're big into the OSR or play with some devoted grognards.
D&D's mechanics balk at lasting injuries, so don't do them. Instead, play a system that supports these mechanics.
A setting that turns crippling injuries into non-crippling injuries. Cyberpunk or science fiction allow for prosthetics and cybernetic enhancements that make the tragedy of permanent injuries into something interesting. Yeah, dude with a seismic maul crushed my scapula, so I had the doc install an upgrade, so I'm swinging twice as hard.
A game that is more narrative in nature, allowing a permanent injury to add to and enhance a character in some way. Fate's Aspects allow things like Ahab's peg leg to matter to the game in a way that's not -10 ft. move speed. Ahab's peg leg drives his desire to hunt down Moby Dick and the game's mechanics reinforce this with Fate points and Compels.
I wouldn't recommend using any traditional RPG for "permanent injuries" except in a few cases, but if you insist...
Stop GMing Badly
Yes. If you run your traditional RPG with GRIM and GRITTY and HARDCORE mechanics, you need to suck less. "Do better," as the modern empty platitude says. That means a couple of things.
First, set everyone's expectations accordingly. Advise the players that playing like a typical D&D murderhobo will result in their characters being transformed into toothless beggars who can't swing a sword because they've lost both arms, an eye, and fourteen toes.
Second, understand probabilities. The characters who will suffer permanent injuries are player characters. Non-player characters will likely be dead before they matter, they'll be minor characters where their injuries don't impact the game, or they'll be largely non-combatants who survive but the injuries are mostly cosmetic. I know you have fantasies dancing through your mind's eye about Gawain the Virtuous hacking off Mordred the Fell's arm in combat only for Mordred to return later bearing that wound as a marker of his defeat...but it ain't gonna happen. What'll happen is that you, as a crappy GM, will toss 3d6+6 bandits at Gawain in an idiotic random encounter, the noble knight will take a head injury that renders him a drooling potato, and that'll be the end of his adventuring days.
Thirdly, don't force combat. Because you insisted on running a traditional RPG, and because most traditional RPGs haven't evolved past "a combat engine with some skills bolted on," the game's mechanics emphasize combat. Workaround: include plenty of player-friendly non-combat conflict resolution options. Unfortunately, because you're a bad GM, you probably think this means "roll a Stealth check, oh you failed, roll for initiative." Notice the phrasing player-friendly. That requires both availability and reliability. Diplomacy, scheming, subterfuge, bribery, manipulation, and creeping about like a cowardly ne'er-do-well should routinely succeed. And "routinely" doesn't mean 50% of the time, it doesn't mean 60% of the time, it means 80+% of the time. Why? Because in a game with any longevity, you're going to see a number of conflicts arise, and if you have twenty potential combats and the players' chances of getting into combat is 50%, and that's ten times the players will probably be rolling on your Grimdark Injury Chart.
Quit Whining, Players
Play with those who are going to be good sports about permanent injuries. That guy who pouts every time he fails a skill check? Yeah, not a good fit for a game with permanent injuries. That guy who excitedly talks about the time that Regoran the Barbarian charged the necromancer only to be slaughtered by a horde of skeletons in an epic battle? Yeah, he's probably down for permanent injuries.