The rule system underlying the fourth edition of the world's most popular roleplaying game.
The rule system itself is under the Game System License, a non–shareable works licence.
- 4SRD ● A project to closely clone D&D 4E.
- D&D4.5 ● A partial clone of D&D 4E.
- Exploding Kingdoms ● Inspired by 4th edition D&D.
- Magic Sword ● A project to clone and improve upon D&D 4E.
- Open4E ● 'This system is intended to be a streamlined and open tactical RPG. The primary source of inspiration is Dungeons and Dragons 4th Edition.'
- Orcus ● A clone of D&D 4E.
- TRIC SRD ● A 4E clone.
- Ultramodern4 ● Dungeons & Dragons 4E rules in a modern setting.