Decisions I'm making today:

First, as many modifications as possible will exist using new or replacement features of existing rules: classes, feats, skills, spells, etc., rather than radical redesign. Second, there shall be heavy limitation on the creatures within my world: Humans, Elan, Goblinoids, Halflings, and Elvenkind will be the only groups elligible to players. Furthermore, I may want to consider rereading and annotating the Dungeon Master's Guide (skimming?) on world and campaign creation.

Second: the map, while not an imitation of the Mediterranean, should have similar geography and feeling, of a small central sea expanded by many smaller component seas (the Mediterranean is added to by the Aegean, Adriatic, and Tyrhennus sea at minimum).

Third: The adventure campaign may instead comprise of a series of dungeons and encounters on a theme, with the onus on a GM to fill in the gaps between the campaign as normal.