Grendel's Cave is a real-time browser-based role-playing video game and MUD. Grendel Enterprises publishes and runs it exclusively on the Internet. The basis for Grendel’s Cave is Anglo-Saxon mythology and Beowulf, and it is set in the historical medieval period. Scholars consider it an artistic depiction of Grendel and the poem, Beowulf, as well as a modern adaptation and a derivative work of the epic. It has been online since 1998. Educational websites use Grendel's Cave as an Internet learning aid for medieval literature and they considered it an online Beowulf resource.