in Disco Elysium I was expecting there to be some kind of “addiction mechanic” that would add a long-term downside to taking drugs, and was surprised not only by the absence of any such mechanic but also that the benefits of drugs greatly outweighed the cost. anyways fast forward to the late game and I was downing three bottles of pyrholidon and smoking an entire pack of cigarettes before attempting any check, and it was only then I realized there was in fact an addiction mechanic
honestly, i think this is why i like the way the game handles substances so much. when i was looking up playthroughs of disco elysium i stumbled across one subreddit thread where someone asked “gameplay wise, is there any point to staying sober?” and just looked at it. like, yeah. yeah, exactly. we know that harry often does drugs specifically so that he can take on a superhuman caseload - as he puts it to kim, to be a “really good detective”. it was so chilling to see a player asking the same exact question that harry would probably be asking himself. without an external punishment mechanic, without being heavy handed about it, and in a way that (as OP pointed out) is so natural as to be almost unnoticeable, it manages to put the player exactly in his shoes as a recovering (or not recovering) addict. it’s a really well-designed mechanic
“Things are harder without this substance, so there’s no reason for me to abstain” being a purely Player-Driven interaction is a phenomenal addiction mechanic. Absolutely fucking gorgeous.