Mr. Spaceship by Philip K. Dick, Science Fiction, Adventure

Set in a distant future, humanity battles the alien "Yuks," who utilize organic life forms instead of technology for warfare. After years of struggle, a team of researchers, led by Philip Kramer, embarks on an ambitious project to create a spaceship powered by a human brain. They enlist Kramer's dying professor as the brain donor, aiming for mechanical perfection. However, their success leads to the emergence of a mysterious entity known as Mr. Spaceship, introducing unforeseen complications to their mission.