Advanced Dungeons & Dragons 2nd Edition vs OSRIC

Compare Advanced Dungeons & Dragons 2nd Edition and OSRIC side by side. See differences in complexity, dice, genre, and more.

	Advanced Dungeons & Dragons 2nd Edition	OSRIC
Genre	Fantasy	Fantasy
Tags	Character Building, Classic Fantasy, Crunchy, Descending AC, Dungeon Crawl, Random Tables, Tactical, Vancian Casting	Dungeon Crawl, Tactical, High-Fantasy, Character Building, Theater of the Mind, Heroic, Descending AC, Vancian Casting
Core Mechanic	Roll 1d20 to attack and meet or exceed THAC0 minus the target’s descending Armor Class. Ability and proficiency checks roll a d20 against an appropriate score. Spellcasters choose spells to memorize before casting.	Roll d20 + modifiers vs. target numbers (THAC0/AC for combat, saving throws for hazards). Ability scores rolled on 3d6, class and level determine hit dice, spells, and abilities. GM acts as referee for rulings.
Dice	d20	d20
Complexity	High	Medium
Availability	Paid	Free core rules
Runnability	4 of 5 book tools	2 of 5 book tools
License	All Rights Reserved	AELF + CC BY 4.0 (SRD 5.1)
Third-Party Publishing	Not yet researched	Not yet researched
Publisher	TSR, Inc.	Mythmere Games
Year	1995	2025
Languages	English	English
Best For	Groups who want referee-led fantasy campaigns with class-and-level characters, prepared spells, optional proficiencies, and detailed combat procedures.	Players who want the classic AD&D 1e experience with cleaner organization, well-defined rules for combat and spells, and a huge library of compatible OSR content.
Highlights	THAC0 expresses attack chances as a single target-number calculation against descending Armor Class. Parallel PHB and DMG organization and a DMG index covering both books make rules topics easier to locate. Optional proficiencies add chosen weapon and nonweapon capabilities to class-based characters.	Faithful AD&D 1e rules reorganized for clarity, large back-catalog of compatible adventures, middle-ground complexity between B/X and modern D&D, free PDF available
Considerations	Core rules remain split between the Player’s Handbook and Dungeon Master Guide, including DM-only procedures. Descending Armor Class, initiative modifiers, and special combat procedures require reference beyond a basic d20 roll. Optional proficiency rules increase character choices and exception handling.	Deliberately old-school: THAC0 and descending AC may confuse modern players, less balanced than modern systems, relies heavily on GM rulings, limited character customization compared to newer games