Chocolate Doom is a Doom source port which aims to behave as closely as possible to the original DOS Doom executables.
There are a number of reasons for having a port which behaves like the DOS version:
* Just Doom. No more. No less. With all the flashy features that have been added to modern ports, it's easy to forget the original.
* DOS is dead. DOS Doom does not run properly under modern operating systems (Windows XP/Vista, Linux, MacOS X, etc). With hardware and software support for DOS fading away, it's hard to see a future where it's possible to play the original.
* Demo compatibility. The majority of demos are recorded for the original DOS Doom. Few ports maintain demo compatibility.
* Testing. Releasing a WAD "for Vanilla Doom" means that it will work on all ports.
These details are provided for information only. No information here is legal advice and should not be used as such.