Thanks again for digging into this. I’ve been looking at 5E as well. The short version of my reply to the above is, now that Medieval Baltic Vol II is finished, I am pivoting back to the Codex rulebooks and have already started work on ‘modernizing’ them. Certain decisions have been made, but the TL:DR is as follows:
1) We are making a streamlined 2021 edition of Core Rules (et al) with most of the 3.5 specific Feats, rules and terminology (like BaB) removed, and some additional role playing rules (as distinct from just combat rules as current) added. This will also have some terminology which is ‘5E friendly’ like using the term proficiency. The 2021 version will be basically ‘system agnostic’ and ‘system lite’ so as to be easier to adapt to 5E or OSR RPG variants.
2) The adventure module, Road to Monsterberg, has already been adjusted somewhat along these lines based on playtest feedback, and will be brought further into sync with this general system reform.
3) Once this is complete we will begin to look at layering in some of the rest of the 5E terminology and rules (by either including them or more often, explaining where they are replaced by Codex rules) so as to be in full compliance with the 5E OGL contract. The goal is to include this in a somewhat modular manner rather than the way 3.5 was tightly integrated into Codex previously. That way whenever the newer version comes out we won’t have this same problem.
4) Then we are going to finish and release the Character Generation book, Codex Ingenium, which will be designed to be 5E compliant (though obviously, it’s different in many ways). Some of the philosophy of the approach we are taking to this has been discussed in some detail here.)
I’ll be glad to bounce this off of you and consult with you on the revisions as they come out, I can definitely use all the help I can get.
As for OSR vs. 5E, that is more of a gamer culture thing. The mainline 5E audience seems to be wedded to some ideas like automatic overnight healing, player character death being frowned upon, automatic spell casting and spell recharge, and so forth, and an overall emphasis on high-magic, high-level play which isn’t really compatible with Codex or the idea of historical gaming. That said, if people want to try to adopt it for that I am 100% ok with it! But I’ve found that whereas 10 years ago Codex was made for people who liked to tinker with rules and fold them in to their own house systems, now days it seems like a lot more of a soup to nuts level of completeness is required for a lot of gamers. So as far as a complete seamless system, we will be adapting to 5E rules, but leaning more toward an OSR game style. Some people do run OSR campaigns in 5E.
Culturally, OSR seems to be a better fit with Codex – at least that is our current conclusion. This is because it’s more typical to have low-magic, low-fantasy settings, without very high level game play or comic -book style super powers and so on, and the idea of player mortality is not a third rail.