MBF

MBF (Marine's Best Friend) is a source port created by Lee Killough after he left the Boom team. It is regarded by some as Boom's successor. As with Boom, MBF was limited to running under MS-DOS.

MBF adds several features:


 * Friendly monsters, including single-player helper dogs.
 * Bug fixes, such as a fix for the blockmap limit (MBF includes an internal blockmap builder).
 * A "beta" mode, in which MBF emulates the behaviour of beta versions of Doom. This includes the BFG 2704, the version of the BFG 9000 included in the beta.
 * Higher-resolution 640x400 screen mode.
 * A means to change the level's sky texture (Linedef action 271)

MBF was originally licensed under the non-free Doom Source License, but Killough has since relicensed his work under the GNU GPL.

MBF formed the basis of the SMMU port by Simon Howard. In 2004 it was ported to Windows with the name WinMBF by the Team Eternity.

Bugs
Due to changes in the collision detection algorithms, a respawned or resurrected monster can sometimes become "glued" to another monster or to a wall. This bug propagated into later ports which used the MBF source, such as PrBoom.