Read: The Maker of Universes
After the imaginative Riverworld series it was only a matter of time for me picking up another Farmer novel. The World of Tiers series seems to be rather closely related as, again, there is an artificial world, some alien überlords playing gods and a bunch of underlings gifted (?) with relative immortality. They can get killed, though they will not die of old age or illness.
Considering when Maker of Universes was written, Farmer sure shows some imagination and original ideas – at least others who came later (like Stargate) seem to have borrowed from him. Compared to more modern works Maker of Universes is short. Too short actually, part of the story advances so fast that you wonder what happened in between, when the protagonist learned something that he should not yet know, that the reader did not know so far. Despite this discrepancy between length of the novel and progress of the story this first novel in the World of tiers series will certainly not be the last one that I read.