The Eternity Engine is a GPL source port for Doom maintained by James "Quasar" Haley and Stephen "SoM" McGranahan. It was originally meant to power the Eternity total conversion, but after the project went on hiatus, eventually being cancelled on the 15th of June 2006, the engine became the prime focus. The engine is based on Smack My Marine Up (SMMU) by Simon "Fraggle" Howard.