Hello there! I've been OSR-curious for a few years now. I like sandbox games where the dice decide reactions, weather, random encounters, etc because that keeps things interesting even for the GM. Incidentally, it also works great for solo play which I like.
However, while the older versions of D&D and retro clones commonly associated with OSR are good games, they're not my preferred type of game. I want the "powers" that newer games gives me as a player, with more mechanics per class. Therefore, I prefer games like Pathfinder over Old School Essentials.
So, while I think I have a decent grasp of what OSR is, I'm not quite sure what NSR is; my impression is that NSR means "playing in the OSR style, but with modern mechanics". Is that correct, or maybe I'm completely off the track?
Effectively, NSR games are games in the OSR spirit (generally, but not necessarily, rules light with a focus on procedural systems that generate experience rather than prescribed plot [though this isn’t always the case with either “school”]) that are not concerned with being immediately compatible with OSR adventures.
Systems like Cairn, Mothership, and Electric Bastionland are all good examples of the NSR.