It's my favorite revamp of a B/X style retroclone, and I consider Beyond the Wall to be a really good example of a "forward thinking" OSR game in all the good ways. It takes the core conceit (B/X style system) then makes the mechanics work for the setting in interesting ways. Then it adds in a playbook format to character design and modules that innovates to teach new players how to run open-ended games, come up with interesting characters, and veterans get a nice suite of tools to play with. All around one of maybe a handful of retroclone style games I feel deserve as much attention as it can possibly get.