The Compendium Hack

...or "How I Play 2nd Edition AD&D".

1. 3d6 assign ability scores

2. PHB 6 standard races + Tieflings (Planescape) + Half-Orcs (Greyhawk)

3. Classes: standard PHB + Barbarian (Warrior group) + Sorcerer (Wizard group, 3E tables) + Monk (Priest group, Scarlet Brotherhood) + Assassin (Rogue group, Scarlet Brotherhood).

4. Favored classes: Unlimited advancement in the following classes:
 - Dwarf: Fighter
 - Elf: Mage
 - Gnome: Illusionist
 - Halfling: Thief
 - Half-Orc: Barbarian
 - Half-Elf / Human: ALL

5. Humans are the only race that can dual-class and always gain +10% XP bonus

6. Cantrips and Orisons: 0-level spells for Priests and Wizards (3E tables)

7. Advantage / Disadvantage and Inspiration (5E) instead of penalties and bonuses

8. Simple Encumbrance (LotFP)

9. Wizards HD is changed to d6; Rogue HD is changed to d8.

10. Weapon proficiencies by Weapon Groups:
-Blades: All swords, daggers, knives

-Bows: longbows and shortbows

-Crossbows: all crossbows and firearms

-Cleaving and Crushing: axes, maces, mauls, hammers

-Flails: Chains, flails, whips

-Polearms: Glaives, halbers, spears, staffs

-Throwing Weapons: Darts, shurikens, throwing axes

-Unarmed

11. Extra group XP: 1XP per 1gp of treasure recovered