From publisher blurb: Old-School Essentials is an adventure role-playing game of exploration, danger, monsters, and magic. The game is intentionally rules-light, putting the focus of play on imagination, improvisation, and fun. The rules are optimised for ease of use at the table, with meticulous attention to wording and layout clarity. What's more, Old-School Essentials is 100% compatible with the classic Basic/Expert game from 1981, meaning that decades of adventure are at your fingertips! Old-School Essentials is a modular game where the core rules of the game are extended by additional "rules modules" which add content for different genres of fantastic adventure. Advanced Fantasy: Genre Rules This book contains the rules for playing games in the Advanced Fantasy genre, bringing in material inspired by the beloved 1970s Advanced rules: 9 human classes: acrobat, assassin, barbarian, bard, druid, illusionist, knight, paladin, ranger. 6 demihuman race-classes: drow, duergar, gnome, half-elf, half-orc, svirfneblin. All new classes are carefully designed to match the power levels of the classic Basic/Expert game. Rules for poisons. (Essential for assassin characters!) Advanced options: Optional rules to add extra depth to character creation, combat, and spell casting. Note that this book is not a complete game!