Osiris has existed since the original Divine Divinity game from 2002 (and was obviously developed even before that). It has been used in every single Larian game since. I wasn't around back then, but I assume it was used/designed because rule-based logic is a natural fit for event-based programming.
I also found Osiris as a language fairly easy to pick up when I applied for a job at Larian (using the
videos created for DOS1). However, it is definitely true that especially in the beginning, it is very hard to figure out what goes wrong when it does, and why.
I have written most of the Osiris documentation from DOS2 based on what I remember was hard to figure out (like how to structure goals to ensure things get initialised/executed in the right order, and how rules get evaluated exactly), but some tutorials from the ground up like there were for DOS1 are definitely also still needed. Fortunately, the base language has remained pretty much the same and those previous videos are still 99% relevant.
