Because the game 's source code had been lost by Rogue Entertainment with its original programmers being contracted to do additional coding for the re-release .
Rogue Entertainment is a derivative of the Chocolate Doom subproject Chocolate Strife was used as the game 's engine .
Because the game 's source code had been lost by Rogue Entertainment , a derivative of the Chocolate Doom subproject Chocolate Strife was used as the game 's engine , with its original programmers being contracted to do additional coding for the re-release .