Out of curiosity, what would you consider the essential non-core sourcebooks for each edition of D&D? The general rules expansions, books of races and classes, and so forth that were considered key additions to the core game. This can be either general observations, or just for your own group.
Ones that seem like pretty obvious general choices off the top of my head:
Ones that seem like pretty obvious general choices off the top of my head:
- Original D&D: All four supplements, but especially Greyhawk.
- Moldvay Basic: Expert Rulebook (the only option).
- BECMI: Expert, Companion, and Master Rules. (Less sure if folks considered the Immortals Rules essential.)
- 1E: Unearthed Arcana (though I gather some considered it pretty broken, I've seen people call the game D&D 1.5 from then onward). Maybe Fiend Folio and Monster Manual II?
- 2E: Not sure here, as there were so many. Maybe the Player's Option books (which I've seen described as part of a D&D 2.5)? Tome of Magic?
- 3.0: Epic Level Handbook, since it wound up in the SRD. Probably also Psionics Handbook and Savage Species.
- 3.5: Expanded Psionics Handbook, since it also wound up in the SRD. PHB II and DMG II. Maybe the 3.5 version of UA?
- 4E: All the additional "core" books (PHB 2/3, MM 2/3, DMG 2).
- 5E: Xanathar's, and Tasha's (which is definitely shaping up to be 5E's analogue to 1E's UA). Probably VGTM and MTOF, until they were supplanted by MOTM.