Chris Perkins' Advanced Dungeons & Dragons 3rd Edition is Chris Perkins (not to be confused with Wizards of the Coast's Christopher Perkins) take on what a 3rd Edition of Dungeons & Dragons should have looked like. It is a mix of Castles & Crusades, D&D 3.0 and 3.5, and AD&D 1st Edition 2nd Edition.
The basic check mechanic is a d20 roll +/- modifiers that must be higher than the DC (Difficulty Class) to succeed. Ability, proficiciency,and situational modifiers are applied to the roll result.
The basic game rules feature:
- Random attribute generation or point buy.
- Character races (dwarf, elf, gnome, half-elf, halfling, half-orc, human)
- Character classes (cleric, bard, druid, fighter, barbarian, paladin, ranger, magic-user, monk, thief, assassin)
- Experience levels with experience point requirements based on the character class
- A Vancian magic system (spells must be memorized, the number of spells per day is restricted by character class and level)
- Multi- and split-classed characters (using two classes simultaneously or switching classes)
- An alignment system with nine alignments
- Skill proficiencies that grant a proficiency bonus to checks
- Saving throws don't have separate values. They are based on the attributes instead.
- Combat has various special attack rules, but the basic attack is a modified roll against the opponent's armor class.