I want to buy and run the B1: Keep on the Borderlands module, but which says 1E on it. I can't find a 1E ruleset for sale though, is the 2E PH, MM, DMG what is used to run B1?
I only played AD&D and then 3.5e, and now 5e. Is the 2E ruleset the same or close to the original AD&D set at least in FG?