I'm going to run an OSR-style game for a group I usually GM Pathfinder for tomorrow. I'm pumped. Since it's a one-shot, I'm going to have less context than usual. As a result, I'm going to make it a display of the things you can do in an old-school style, which is, in my humble opinion, everything you can do in the new-school. In particular, I'm going to single out something that gets a lot of attention as being a strength of 4e: exploitation of terrain features.
I think I'll have the opportunity for chase or combat in an abandoned,
multi-storey temple of some sort; I want to exploit the verticals. And
I'll have some rubble to create rough terrain, and perhaps have the
whole outdoor part take place while it's raining, so smooth surfaces
become slippery and soil becomes mud. It'll be an opportunity for
players to find and exploit cover and partial shelter, to try to funnel
enemies into single-file formations, that sort of thing.