That's what I did when I ran Primeval Thule. Worked well. I limited the amount of magic quite a bit, so the spellcasting progression of someone with all three feats was 4/2/1. OTOH, I allowed characters with the Sorcerer feat to attempt rituals to cast spells of a higher level than their slots, with some risk.
Posting the feats in case it's useful to someone.
Magic Initiate:
Prerequisite: Intelligence 13. You learn two cantrips and one 1st-level spell, and you gain one 1st-level spell slot. Your spellcasting ability modifier is Intelligence. You may choose your spells known from any spell list or combination of spell lists. For example, you could choose
guidance,
shillelagh and
hex. Spells must be thematically appropriate to a sword-and-sorcery campaign. As a rule of thumb, most abjuration, enchantment, illusion, and necromancy spells are in; splashy evocation and conjuration spells are out. It’s possible we could “refluff” some spells that would otherwise be a bad fit. For example,
magic missile could be reworked as
agonizing pain, which simply inflicts necrotic damage in the specified amount upon the target of the spell. When in doubt, just ask. When you take this feat, you also become eligible for the next feat in the spellcasting feat chain (see Magic Adept, below).
Magic Adept
Prerequisite: Magic Initiate. Your exploration of the dark arts is progressing nicely. You gain the following benefits:
- You learn one cantrip, two 1st-level spells, and one 2nd-level spell, and you gain two 1st- and one 2nd-level spell slot.
- You gain the ritual spellcasting feature, allowing you to cast any known spell that has the ritual tag without expending a spell slot.
- You can use magic items restricted to any spellcasting class, though these items are exceedingly rare in Primeval Thule.
Sorcerer
Prerequisite: Magic Adept. Your mastery of things Man was not meant to know is nearly complete.
- You learn one cantrip, one 1st-level spell, one 2nd-level spell, and one 3rd-level spell, and you gain one 1st-, one 2nd-, and one 3rd-level spell slot.
- You can learn new spells from scrolls, grimoires, and similar sources.
- You can learn and cast spells with the ritual tag of a level for which you do not have spell slots. To perform such a ritual, you must make a sacrifice unique to each ritual spell, and you must make an Intelligence (Arcana) check with a DC equal to 10 + the spell level to complete the ritual successfully. Finally, you must make a Madness check with a DC equal to 10 + the spell level or gain one affliction from the Madness Table.