Re-writing D&D 5e without having actually ever read them.

DUNGEONS & DRAGONS, FIFTH EDITION

1. Roll 4d6 and drop the lowest, do that six times, assign to the six ability scores: Strength, Intelligence, Wisdom, Constitution, Dexterity, Charisma.

Subtract 10 from your score and halve it to get your ability score modifier.
So 18 - 10 = 8, divided by 2 makes it a +4 modifier. 6 -10 = -4, divided by 2 makes it a -2.

2. Choose a Race:

Human (you know what those are)
Elf (high elves get a cantrip, wood elves can talk to animals and dark elves see in the dark)
Dwarf (there are only one kind of dwarves, the angry drunken kind)
Hobbit (like dwarves but more boring and weak and british instead of scottish)
Gnomes (why? why are there even more dwarves? Ok, techno-dwarves, fuck it)
Tieflings (queer half-demons from hell, get a fire cantrip, or an ice cantrip if you're from cold hell)
Githyanki (I played like 2 minutes of Baldur's Gate 3 and these guys are cool now so here you go)
Ducks (I'm making the rules, you can be a cartoon duck from Glorantha now, treat as small humans)
Anything Else (yes you can be a dragon, yes you can be a goblin)

3. Choose a Class:

Fighter: you hit good. Add your level to attacks and damage rolls, or split your bonus between attacks equal to up to your level. Get 10 HP + CON at the start and d10 + CON HP per level past the first. You can cleave (that means if you kill a dude, make an extra attack).

Barbarian: you hit gooder. Like a Fighter but you can't wear armor but you add your CON bonus to your AC instead, and you get 12 HP + CON and d12 + CON past the first level and you can RAGE which grants you an extra move and attack per turn but if there are no enemies left, make a DC 15 save + WIS bonus or start attacking whoever is around until knocked out. You can cleave.

Ranger: you hit good at a distance and have a animal friend and are very woodslandsy and outdoorsy. Add your level to any roll that's like tasting a creature's poop to know its exact weight and stats or orient yourself etc, you know what a ranger is. Like a Fighter but light armor and no two-handed weapons as a trade off for your ranger stuff.

Paladin: for fuck's sake. Like a Fighter but you can also lay on hands and ride a magical horse that shows up at level 5 or something, and at level 10 it's a griffon now or a dragon if you're an evil paladin which I think are called blackguards. And you have to follow your God's rules, otherwise you lose the special paladin stuff and become a normal fighter FOREVER. Also you know what? You need 17 CHA to unlock this class, boom, AD&D style. Balance restored. I'm a fucking genius.

Rogue: thief-assassin-acrobat all-in-one. Add your levels to do all the thiefy roguish stuff. Your backstabs are always critical hits if they hit. Also add your level to attacks made on unaware targets. Play like a sneaky rat. You get d8+CON HP (so 8+CON at 1st level). Obviously only roguish weapons and no metal armor.

Cleric: you're like a fighter but your HD is d8 and you can't use edged weapons for mysterious reasons (I don't care who your god is, NO EDGING ALLOWED). You can pray for your God to do things related to its domain, you get one prayer answered automatically per downtime per level, past that you roll reaction rolls modified with your CHA to see if God listens. Higher level clerics = higher level miracles. As with Paladins, if you fuck up, you're OUT and you're a Fighter with less good HD. Also add your levels to attacks against the undead, vampires, werewolves etc, alternatively against enemies of your faith.

Wizard, Sorcerer, Warlock: yes they are the same thing, no it does not need three different mechanical frameworks. You get d6 HD because 5e is for babies who are scared of playing a d4 HD class even when it is a walking talking nuke. You can only use shit weapons like daggers and staves and you can't wear armor and do magic or you explode. You get 3 starting spells, then an extra spell per level. At first level you can cast one spell safely, every spell hereafter requires you to make a save vs Magic or bad things happen. The stronger the spell the badder the outcome if you fuck up a casting. Make up the spells based on your wizard's school or your sorcerer's bloodline or your warlock's patron.

Bard: you're a rogue with a guitar.

Monk: you get d10 HD and add levels to attacks and damage when unarmed only, and as long as you're unarmed and wearing no armor you also add your level to your AC. You also add your levels to rolls when doing monk shit like running on walls and climbing stuff and meditating. You can do the equivalent of lay on hands but it requires performing a tea ceremony.

4. Feats (optional)

No.

5. Equipment

You can carry two items in your hands (unless you have more than 2 hands), two items on your belt, six items in your backpack. Tiny items can be written down on the same line, use common sense. If you carry more, you're overburdened and get a disadvantage dice on all rolls (including damage etc).

Your purse is empty and you owe a thousand gold to the nearest mid-level bad guy like a Thieves' Guild Godfather or a crooked sheriff. Go make money.

6. Alignment, Languages, Bonds, Secondary Skills

You speak the local common tongue + as many bonus languages as your INT modifier if positive, but every one past the first is like, not as good. If you have 2 languages you're fluent in both, the third you're good at but not fluent, the fourth you're OK with, etc etc.

Alignment is made up of 2 adjectives like "Lawful Stupid" or "Vicious Sexy". Play your lil' guy according to your alignment.

Bonds: for every character, figure out who they're currently fucking, who they had a thing for before and ask the other character if that was requited or if they're like exes or frenemies now, who's their best friends, and so on. If your adventurer is assexual and/or aromantic, adjust accordingly. Who's your queer platonic Extra Bestie or whatnot. Seriously do this it's essential to the 5e vibe. It'll turn your sessions into Apocalypse World, in a good way.

Skills: for each ability score, write down as many skills as you have + modifiers, these are things you're extra good at which either allows you to try shit unskilled people couldn't even try (like alchemy) or that give you situational bonuses (I dunno like +2) if it makes you better at it but everyone can do it (like cooking). You also get Shit Skills for your negative modifiers if you have any. These are things your guy sucks at. Like cooking or animal husbandry or whatnot.

7. Go Kill God or Something

To do stuff, say you're doing it. When taking a significant risk etc, the GM will ask for a dice roll, which is d20 + relevant stat mod + any other modifiers they can think of, vs whatever target makes sense at the moment. 15 for something tricky but doable is a good basis. Don't roll to know shit or for perception or whatever.

In a fight, everyone says what they wanna do then everyone rolls d20 + mods to attack vs ascending Armor Class, stuff happens in descending order attack roll totals. So if someone rolled 27, they go first. Damage is based on weapons, like d4 for a improvised weapon, d6 for a light weapon, d8 for a martial weapon, d10 for a heavy weapon, d12 for the biggest weapons, etc. Add STR or DEX to hit and or damage depending on whether the weapon is for brutes or sneaky gits. If you're a Warlock or a Bard you can add your CHA instead cause your passive-aggressive glibs hurt more than your attacks. You know what just pick whatever ability score modifier you feel would work best for your character's vibe, you'd spend a feat to get that anyways if we were playing the worse version of this.

If you get to 0 HP, you're dying, save or DIE. If you fail, you're dead. If someone resurrects you (and I don't think a Cleric under level 9 should be able to do that, let alone scrolls, and no buying scrolls or magic items at the local shop that's stupid), you lose 1 permanent CON. If you succeed you're just KO and will bleed out in one hour if left unattended.

Rests take like ten minute and restore half of the HP you lost during the last fight.
After that you recover 1 HP per night of rest, or all your HP during Downtime (at least a week).

8. Levels

Aaaaa you need 2,000 XP to reach level 2, then double the new value for every level, max level is 9th.