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:
“We were that generation called “silent,” but we were silent neither, as some thought, because we shared the period’s official optimism nor, as others thought, because we feared its official repression. We were silent because the exhilaration of social action seemed to many of us just one more way of escaping the personal, of masking for a while that dread of the meaningless which was man’s fate.”
—Joan Didion (b. 1935)
“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)