The Magic Labyrinth/Riverworld

The fifth book of Philip Jose Farmer's Riverworld cycle begins a few weeks after the supposed final resolution and revelations.
    The nine survivors of the quest for the Tower are:
  1. Loga, the renegade Ethical
  2. Sir Richard Francis Burton, 19th century writer and adventurer
  3. Li Po, 8th century Chinese poet
  4. Alice Pleasance Liddel Hargreaves, the historical basis of Alice in Wonderland
  5. Tom Turpin, ragtime pioneer
  6. Aphra Behn, 15th century writer and spy, the first Englishwoman to make a living as a writer
  7. Peter Jarius Frigate, 20th century SF writer (loosely based on Farmer)
  8. Nur ed-Din el-Musaphir, 11th century Sufi
  9. Jean Marcelin de Marbot, 17th century warrior, basis for Arthur Conan Doyle's Brigadier Gerard stories
As the book opens, Loga is speaking to Burton on a wallscreen when he abruptly liquifies. The eight rush to his apartment in the tower to find only a huge pool of blood. They surmise that an unknown enemy (dubbed the Snark) is in the Tower with them. The only steps they can take are to learn exactly what the computer will permit them to do, and to watch each other's backs.

They have almost complete control of the workings of the Tower, including the ability to selectively ressurrect dead Riverdwellers in the Tower -- but there are still no rebirths on the River itself. They also cannot order the computer to tell them anything about the Snark. Eventually they decide to move into larger rooms. In the Tower are twelve triangular chambers, 400 feet high by 5 kilometers long. They each select one and redecorate to their specifications. Alice creates Wonderland, Frigate an antebellum plantation in the Jurassic, Burton an Arabian Nights, etc. Turpin, more ambitious, creates Turpinville, a gold plated fantasy redlight district in which he is the undisputed Boss.

And Boss he is. The travelers have started ressurrecting people, old Earthly friends and lovers, acquiantances from the River, and more than a few wildcards, such as the three men who were Jack the Ripper and their victims. It does not take long for things to get completely out of hand. Turpin gets thrown out of his own kingdom. Alice throws a huge party, which ends in bloodshed when the Snark takes control of her Wonderland androids and causes them to attack the guests. Turpin's world is destroyed by plugging the drains on his fountains, drowning everyone inside in millions of gallons of bourbon.

The Snark is unveiled as Loga. He was lying about nearly everything. No one attains Nirvana through ethical advancement. The purpose of the Riverworld is to determine who among humanity can handle immortality (about 40%). If you can handle it for 100 years, you are reborn on the depopulated but refurbished Earth. Loga's one truth was that he did everything, nearly destroying the whole project, to extend the time for his own family.

At the end, the last survivors vanquish Loga (who is quite insane) and ressurrect most of their companions from the long journey up the River, including Joe Miller (but not Samuel Clemens, apparently). They are waiting for the Ethicals to return from the Gardenworld and deliver them to Earth, except for Burton, who has been eyeballing the starship in the Tower's hangar.

He waved his hand to indicate the stars.
"Who's going with me?"

Here ends the saga of the Riverworld.