0th Level Characters in 5e

Note these 0th-level houserules are intended more for an adventure like the classic N4 Treasure Hunt, not a DCC-esque funnel game where every player controls multiple 0th-level PCs with the expectation most of them will die.

Waxing Lyrical About N4

(forgive this indulgence, skip down to the 0th level rules if you want)

My first attempt at DMing 5th edition was an adaptation of N4. I adore this module ever since I played in it under Pathfinder rules, though it certainly has its flaws. As-written it's a massive railroad -- my Pathfinder GM did a very good job of concealing that from us -- and it leans a little too much towards verisimilitude. There are two long-abandoned buildings whose room keys are largely iterations of "ruined furniture", "tatters of tapestries", and "chests of moldy garbage".

But the module has its cool moments, and playing at 0th level was my first real exposure to old-school paradigms of "avoid combat unless you can make it completely unfair in your favour", "emphasise player creativity over a long character sheet of class features", and "de-emphasise ~builds~, let characters grow organically based on their choices and mistakes".

I really recommend more new-ish players (I started playing in 2005 under 3.5 rules) give 0th-level play a try. After all, if you end up hating it, you'll soon be at 1st level, and you'll have some sense of the party dynamic so your GM will know what adventure material (official or homebrew) would be most fun to run for the group.

The Korinn Archipelago is also a great mini-setting that can be standalone, or segue into most of the official D&D hardcover campaigns. While the adventure doesn't mention the Realms, surviving PCs are canonically just a few days' longship travel (260 miles) from Waterdeep.

excerpt of "Map of Faerün", by Mike Schley

0th Level Rules

I've tried to explain my choices so that you can better decide what to keep/change.

For each ability score in order, roll 4d6 and drop the lowest. You may then swap one pair of scores, before applying racial adjustments. This is to discourage too much pre-planning about what your character will become. To completely minimise preplanning, I'd remove the ability to swap two scores, and run a game such as Swords & Wizardry or Whitehack where ability scores contribute very little to combat or spellcasting capability. Or a game where ability scores advance faster, e.g. The Black Hack and its various descendants. But this is for use with 5e, and I didn't want to completely remove customisation.

Choose a race and background, but no class. You get any corresponding features and proficiencies. However, if this would give you an at-will spell (e.g. high elf) it is only usable once per short rest. Once you reach 1st level, the spell becomes at-will. This is because N4 starts the characters in a shipwreck situation where they have to scavenge for weapons, and I didn't want to trivialise that with at-will magic attacks.

Starting HP = 6 + your Con modifier. You have no Hit Dice for short-rest healing.

Your proficiency bonus is +2. You have proficiency with simple weapons, but no armor or shields. Racial traits may give you extra proficiencies.

You start with the normal equipment for your background (i.e. no shopping from the equipment list) but a character with a variant/custom background might start with modified equipment, subject to GM approval.

Anyone can attempt to cast from a found spellbook, pray to deities for a miracle, or do other class-specific things, with a successful ability check. Attempting such class-specific things, or wearing armor & martial weapons in combat, is the key to leveling up into a class. Note that success/failure is not important, only whether you've tried in situations that have stakes.

The GM may decide to model characters slowly learning proficiency in something. Perhaps after two combats wielding a looted greatsword, you add half your proficiency bonus to attacks with it. Perhaps after enough study/experimentation with a spellbook, or immersion in the sacred poisonous waters of Lunulata Lake, you can cast a single cantrip.

You become 1st-level when the GM says so. They may restrict your class choices based on what you've attempted. GMs, be lenient with this. It's no fun saying "you can't be a wizard despite studying those spellbooks, because you also tried wearing gambeson and swung a longsword", though you could say "have you considered becoming a bard instead?". A character classing into druid might have to forsake metal armor from then on, but let a nature spirit appear and offer them that ultimatum. This might mean characters end up with an extra weapon proficiency pr something, but that can be their reward for reaching 1st level the hard way.

The GM might instead choose to start you at, say, negative 300 XP. But with combat so dicey at 0th level, this is only recommended if there's plenty of opportunities for non-combat XP.

When you reach 1st level, revise your HP to the "starting" HP for that class (and gain a Hit Die), note any new class features, choose some proficient skills. Your GM might let you choose skill proficiencies based on your actions, even if they're not on your class list. Your class's starting equipment doesn't pop into existence, so hopefully you found some neat stuff as a commoner :-)