It was unique in the way it was made, when it was made, it was a game that visualised 3d gaming before computers were ready for 3d games.

the reason for it to be ported to anything, is a mix of the source code being public for modding and the fact that the game is a 2d game looking and playing like a 3d game.

the real reason, Doom was and still is an awesome game and doom is the grandfarther of all shooters today.