Making It Yours
Fifth edition has carried twenty years of homebrew on its back, and this project is built to continue the tradition. Some well-worn paths, lightest touch first:
House rules first, schema second
Most table variants — critical fumbles, drinking a potion as a bonus action, slow natural healing — need no schema work at all: write the ruling into an always-on GM instruction (or a Rules/ page it cites) and play. Promote a variant into schemas and formulas only when it changes numbers the sheet computes. When you do, chapter 2's order of preference applies: computed field over stored field, stored field over parallel copy, and always both halves of the pair — rule text and runtime.
New content in the existing grooves
The fastest expansion is more nouns: spells, monsters, magic items, feats, a fifth background. Chapter 3 has the per-type conventions; the integration contract (shared bonus fields, honest property flags, 2014 wording) does the rest. A new subclass is one file with parentClass and its featuresLevelN at the right 2014 entry points; a new race is traits plus abilityScoreIncrease fields and it applies itself to every sheet that picks it.
Building a setting on top
The system layer is setting-agnostic; Emberhollow is the model for everything above it: a location file with hooks (@Missing file), a faction with an agenda (@Missing file), lore that gives the place a buried past (@Missing file), a major NPC as a full character (@Missing file), an encounter balanced by the printed budget (@Missing file), and a game start that opens mid-scene with a honey-cake and a crypt door (@Missing file). Replace the village, keep the shape. Set the project's image style once in settings so generated art lands in one world.
Changing editions — don't, here
The tempting hack is backporting 2024 material: mastery properties, origin feats, background ability scores, the revised exhaustion. Resist it — those aren't additions, they're a different rules skeleton (the sibling 2024 project already has one, with schemas to match). The 2014-isms are load-bearing: formulas assume racial increases, subclass fields assume 2014 entry levels, @Missing file instructs against imported wording. Mixing editions produces a game that argues with itself.
Shipping it
Before you publish a derived project: keep the SRD 5.1 attribution statement in the project settings, add an honest list of your changes, use no Dungeons & Dragons or D&D marks and no product identity beyond the SRD — no beholders, no named settings — and make your own cover art. The Creative Commons license is why this project can exist; passing it forward intact is the whole price.