Short take - Old-School Essentials is probably THEE OSR Ruleset on the market today.
Old-School Essentials Advanced Fantasy Player's Tome is OSE's take on AD&D.
If you've never checked out Old-School Essentials, today's Deal of the Day, Old-School Essentials Advanced Fantasy Player's Tome is half off the regular PDF price - 15 bucks down to 7.50
Complete Player's Tome
- This book contains the complete game rules, 13 fantastic classes (acrobat, assassin, barbarian, bard, cleric, druid, fighter, illusionist, knight, magic-user, paladin, ranger, thief), 10 classic races (drow, duergar, dwarf, elf, gnome, half-elf, halfling, half-orc, human, svirfneblin), full equipment lists, and over 200 weird and wonderful spells (complete cleric, druid, illusionist, and magic-user spell lists).
- Simple rules let imagination and fast-paced action take the spotlight.
- Clear, modern presentation makes the game easy to learn and quick to reference.
- Compatible with decades of classic adventures and supplements.
Old-School Essentials comes in two flavours: Classic Fantasy (based on the 1981 Basic/Expert rules) and Advanced Fantasy (the same game, massively expanded with content inspired by the 1970s Advanced 1st Edition rules).
This book includes all core rules and player options from the Classic Fantasy Rules Tome plus the Advanced Fantasy Genre Rules and Druid and Illusionist Spells supplements!