Retro RPG: Labyrinth Lord

        Labyrinth Lord (LL) is a 2007 fantasy role-playing game written and edited by Daniel Proctor and published by Goblinoid Games. It emulates the rules and feel of Dungeons & Dragons (D&D) using the Open Game License (OGL) from Wizards of the Coast. LL is based on the 1981 D&D Basic Set edited by Tom Moldvay, and its accompanying Expert Set by David "Zeb" Cook.
        Any adventure written to be played with classic D&D can be run using LL with little or no adjustment. However, there are a few differences between the two games. It extends the rules so characters can advance to 20th level (the 1981 Expert set only included levels up to 14). In addition, the cleric class in LL can cast spells at first level, unlike in the 1981 rules.
        Goblinoid Games was the first retro-clone publisher to both make most content open under the OGL and create a free trademark license with few restrictions. The material contained in the LL rules is available to others with few restrictions, allowing fans and other publishers alike to create their own derivative material for use with the system.