Doom is one of the most widely ported video games in the first-person shooter genre: starting with the original MS-DOS version (released as shareware on December 10, 1993), it has been released officially for a number of computer operating systems, video game consoles, handheld game consoles, and other devices.
Once Doom's source code was released into the public under the terms of the GNU General Public License in 1997, several unofficial adaptations were created by fans for many others still.
Some of the ports are replications of the DOS version, while others differ considerably, including modifications to creature design and game levels, with some ports even offering levels not included in the original version.
Famous quotes containing the words official and/or versions:
“Well, on the official record you’re my son. But on this post you’re just another trooper. You heard me tell the recruits what I need from them. Twice that I will expect from you.... You’ve chosen my way of life. I hope you have the guts enough to endure it. But put outa your mind any romantic ideas that it’s a way to glory. It’s a life of suffering and of hardship and uncompromising devotion to your oath and your duty.”
—James Kevin McGuinness, and John Ford. Lt. Col. Kirby Yorke (John Wayne)
“The assumption must be that those who can see value only in tradition, or versions of it, deny man’s ability to adapt to changing circumstances.”
—Stephen Bayley (b. 1951)