This game reminds me of Clifford Simak's Desertion - a short story about humanity trying to conquer Jupiter. By altering men's into completely another lifeform - into Lopers. The idea was to shapeshift a human into a new body and keep the mind, and shapeshift back when necessary. But that did not work, at least for the first four men. The story protagonist is the 5th one, and before transformation, he is tasked with one mission - just to come back from Jovian landscapes to prove that it is possible - to go back.