Halo: Combat Evolved build 268 is an early prerelease build of Halo: Combat Evolved for PC. The build has a timebomb and will not work on newer versions of Windows due to the issue of SECUROM files being blocked, unlike its release counterpart.
This build's documentation claims it is a Beta 1 build and was tested as part of the summer flight for the game. The details for the flight outlined involves mainly testing the game's 9 currently available missions.
This build currently has no available CD-ROM patches, making it impossible to play.