ToME WikiUmoria was the Unix port of Moria. It is the ancestor of several variants, including BOSS and Angband. Angband is in turn the ancestor of its variants, including ToME.
Moria, a Pascal program, had been the first roguelike game for VMS. Why port the program to the C language and Unix? Well, BSD Unix and commercial Unix had spread farther than VMS in some universities and businesses, so a Unix version would allow far more persons to play the game. Moria already had public source code and allowed noncommercial redistribution; Robert Alan Koeneke said it was okay to modify the sources to do the C language port.
As a different set of developers worked on VMS Moria and Umoria, some gameplay differences developed between VMS and Unix. (In contrast, if you played vanilla Angband 3.0.6 or ToME 2.3.3 today on any supported operating system, you will be playing the same game regardless of operating system.) Meanwhile, C was available not only on Unix, but also on DOS and some other platforms. Thus Umoria was the basis for ports of Moria to some other operating systems.
Meanwhile, various persons experimented with the gameplay, creating variants. The last version, Umoria 5.2.2, appeared long ago, but one variant, (vanilla) Angband, continues in development today.