The much hyped DeathWalk feature went through five incarnations before arriving at the shipped version. The original design had death wraiths attacking in the environment after the player died in battle, but this wasn't fun in closed environments. In the second incarnation, this was changed to always take place in an open environment called the underworld. The player would have to stay in the center of the arena while death wraiths attacked and tried to knock the player off the arena until Tommy's spirit power restored to full. This proved too complex a process to ship. Fighting the death wraiths to restore life was added in the third version. The third version also added the concept of Tommy's physical body falling back to the natural world, however it would rise back up if the player stopped shooting wraiths, bringing a final death. This also proved too complex, and was not fun for testers. The fourth version was pretty close to the final version of the game. Tommy's body now lowered itself to the physical realm on a timer, and the player would shoot spirit wraiths until Tommy was fully lowered, and health wraiths quickly after. In the final version, this was changed to shooting both health and spirit wraiths while Tommy's physical body is restored.
As of 2005, the game has been in development for nearly an entire decade. 3D Realms originally announced Prey in 1995, but after several years of development it was put on hold in 1999. Technical difficulties were cited, and one of the game programmers commented that the game's most highly touted feature, "portal tech" was just too ambitious for its time. Portal tech was a feature that could dynamically create rips in space allowing portals to be generated on-the-fly. In 2001, 3D Realms quietly restarted development of Prey, this time outsourcing it to a development group called Human Head Studios, and using the new Doom 3 graphics engine that was created by 'id Software'. However, 3D Realms did not officially confirm the reemergence of Prey until early 2005.
Even though Human Head had a pretty open canvas when starting development of Prey, there were a few elements from the original Prey design document they were not allowed to remove from the game. The game had to have a Native American who had been unhappy with his heritage as a protagonist. This person had to be abducted by aliens, and that protagonist had to use his heritage as a weapon against a technically superior alien species. Also, since portals had been such an important part of the original Prey, they also had to appear in the game.
In the original design document of the game before the project restart, the character of Tommy was originally Talon Brave. Although the main character's name was changed after the restart, the name "Talon" was moved to be the name of Tommy's spirit hawk. This name was not accidental, it was a nod to the old version of the project.