From the Back of the Core Rulebook:
Enter a world filled with labyrinths, magic, and monsters! You can take the role of a cleric, dwarf, elf, fighter, halfling, magic-user, or thief on your quest for glory, treasure, and adventure! This is a complete role playing game. All you need are a few sheets of paper and some dice. Welcome back to a simpler old-school gaming experience. The Labyrinth Lord awaits your arrival. Can you survive the dangers of the labyrinth?
Labyrinth Lord is a retro clone game based on the Moldvay-Cook version of Basic and Expert Dungeons & Dragons.