Sierra High Res Adventure #6. The Dark Crystal is closely based on Jim Henson's film of the same name. You play as Jen, the last survivor of the Gelfings, a race of mole-like people of a distant world. You must find the dark crystal and its broken shard, and repair it to end the reign of evil from the land. This was Sierra's last adventure game before the groundbreaking King's Quest. Gameplay, like all of Sierra's previous adventure games, was entirely text-based with non-interactive, un-animated graphics to illustrate the areas. The only change is that Jen is usually part of the illustrations, technically making it third-person instead of first-person.