I think many gamers have wondered, how they would fix D&D. Of course, there will never be a consensus, but this is my take.
Keep the 6 abililty scores, attack & damage rolls, hit points and spell slots.
This is important to keep things D&D. Splitting between prepared spells and slots like D&D5 does or the 3.5 Spirit Shaman did, is fine though. Binding special abilities to Bloodied (below 50% HP) is a nice idea from 4e.
Make sure that rolling for ability scores is viable.
To do this, ability scores may not improve your attacks or spell casting. You will not automatically add strength to attacks or damage (or another attribute for that matter), nor will you get more or harder to resist spells from high abilities.
Ability damage is a good thing.
We can use it to get mostly rid of binary saving throws too. So a Suggestion spell might be: Take 1dX Wisdom damage or do me a favor. The player can choose. Petrification might do straight Strength damage and if it brings you to 0, helllo, you’re a statue. Of course, all six stats must have ample effects that target them. You want your stats high. Dump stats are dangerous.
Everything is a class.
Building characters in D&D should be fun. Options are fun. Especially when they have both some cool powers and some lore. The problem is that D&D has plethora of kinds of options. Races, classes, subclasses, subraces, paragon paths / prestige classes, alternate class features / kits, feats. Not all in every edition. There are problems with each. Making a 20 level class is hard; you don’t do that at home. Feats are more or less bland. Prestige classes / paragon paths can only be taken at a certain level and might not fit naturally in the narrative. Subclasses are tight to the main class.
Instead, I propose short classes only. Three to five levels each. You can have a few classes open, say 3, but then, finish one before opening the next. Most everything that ever was class-y in any edition of D&D can be turned into such a mini class. There would be Wizard class and a Necromancer class. You don’t have to be a Wizard first, you can start Necro, if you want.
You can take levels in Elf, if you want. This might be because you have Elven heritage, because you grew up with elves, or because you are fanboy and fascinated with elves. D&D 3.5 actually had elf and dwarf classes with 3 levels. That’s where I got this idea.
For newer players there should be suggestions what class to take after this one.
Simple Weapon Groups
The longer the weapon list, the more samey they will appear and the less different ones people will pick. Instead make a hand full of distinct weapon types (Heavy Weapons, Long Weapons) that offer distinct advantages.
Domains for everyone
Spells come in short groupings, like a Cleric’s Domains in 3.x / 5e. Your classes might give you access to certain domains. You know the spells then. Having short domains instead of humongous spell lists is easier to grasp, easier to extend and easier to balance. Choosing just any domain should be a rare thing.
You might want Combat as a mage and Magic as a fighter.
In 3.x there were prestige classes that were for casters and those that were for other people. That is to be avoided. I imagine two common progressions that one might get from class levels. So a level might offer +1 Combat or +1 Magic. And this adds up over all classes. This is pretty similar to what prestige classes did. Magic of course determines your spell slots and Combat your attack bonus and damage bonuses.
We have to make this palatable to the other group though. For example a character might allocate Combat to defense instead of offense. Some dodging might be nice for casters too. There should definitely be a limit there, though.
Magic is a bit more difficult, but as a first step we might power all weird class abilities with slots. A barbarian’s rage is certainly magic. We don’t have to count smites, ki or psi separately either. Another thing that might take spells slots are magic items and blessings. You might not have learned a fire spell, but this fire sword let’s you burn your slots as if you had. This would be a simple way to do attunement or items that grow with you. Something that always felt haphazard in D&D.
Scrolls are spell spellbooks and vice versa
OK. This is a small one. But it makes sense to me. The Wizards ability would simply be to remember the content of a scroll and cast it from memory. If you find a Wizard’s spell book, you can burn through it as if you found a bunch of scrolls.
Other stuff I like
The up to three, successively more difficult attacks per turn from Pathfinder 2. Special attacks on odd or even rolls from 13th Age. Action Dice / Expertise Dice.
Sea Cucumbers and RPGs 