Eternal is a free scenario for Aleph One, first-person-shooter engine derived from Bungie's Marathon engine. It continues the story of the Marathon trilogy, and is a nearly total conversion.
- Fifty-two new levels, some revisiting familiar locations from the original Marathon trilogy.
- Over six hundred fifty new high-resolution textures, including a dozen original landscape textures, from a variety of human and alien environments.
- Eight all new weapons, many of which must be scavenged from your defeated enemies.