I have claimed for decades that my favorite edition of The World's Most Popular Tabletop Role-playing Game is Aaron Allston's 1991 Rules Cyclopedia. And then my old college chum started an OSE campaign and I came to realize it was basically the best parts of the RC, cleaned up and laid out in a more sensible, usable fashion. If you & your gaming pals like anything from the Old School Renaissance, OSE is very likely to become your go-to interpretation of how to roll goofy dice and pretend a goblin just perished. It is SO good, and SO fun, and not encumbered with a lot of the bells and whistles that - while sometimes satisfying - tend to bog down "modern" editions. Well worth the handful of electrum.