Riven

Riven was the fifth Age written by Gehn. It was probably one of the better Ages he Wrote, in terms of size, technology, and stability. Gehn was extremely devoted to this Age and its well-being - perhaps unusually so, given his callous disregard for his other Ages and their inhabitants - because Gehn maintained a number of very powerful misconceptions about the power of the number five, especially as it pertained to D'ni culture. However, despite this fact, Riven still had many fatal flaws in its writing, as all of Gehn's Ages did, and it was in a state of steady decline. Gehn had attempted to convince his son Atrus to fix the Age's instabilities for him, but ultimately his plan backfired. Atrus managed to trap Gehn there for 33 years, keeping him from writing and affecting more Ages.

During this period in Riven's history, the original island split into five different islands. Gehn restricted four of those five islands to himself and those working closely with him. The other villagers were limited to the island on which the village remained. Gehn devised a transportation system for getting around the islands, at first using bridges and then moving to single-seat "mag-lev" cars. Gehn used one of the islands as a Book-making island, one as a temple island and as the location of a large power dome, one as a map island, and one as prison island. Gehn's prison island was actually where the great tree of Riven was once located. This was a huge tree that had once towered above the island, but had been cut down by Gehn as part of his Book-making experiments after Atrus trapped him. Gehn built a office on the huge stump of this tree. Once Age 233 was written and powered by Gehn, the old office became a prison for Catherine.

Riven's inhabitants ended up splitting into those who followed Gehn and those in rebellion against him (the Moiety). Atrus wrote several improvements into the Age, but it was only a matter of time before Riven collapsed completely. Riven's total and utter collapse happened after an unnamed friend of Atrus's had trapped Gehn and freed Atrus's wife Catherine, who had been trapped there. After all of the villagers had been safely moved to Tay, Atrus's friend opened the Star Fissure, which signaled Atrus but also triggered Riven's final collapse. Riven's dead Descriptive Book was kept in Atrus' study in Tomahna until the events of Myst III: Exile; after the fire in the study, its condition and whereabouts are unknown.