Xen's Maps?

Just how many maps Xen Chapters are? Is it 12 like in Half-Life 1? If it is, these are my guess for the amount:
Xen - 2 maps
Gonarch’s Lair - 3 maps
Interloper - 5 maps
Nihilanth - 1 map
Endgame - 1 map

Still skeptical about Nihilanth’s amount of maps as the mapname is called: bm_c4a4a. Does this mean there is a second map? In Black Mesa, every chapter does not have a single map. Endgame makes sense as it is only a single map even in the original.

Maybe, as there is no way to tell without getting an answer from the devs.
The devs (like all sensible people) follow their own naming conventions.
A breakdown if you care

bm_c
It is a black mesa map (or something, the’re all consistent)
4a
The section number. The sections are 0a (Inbound), 1a (AM-BP), 2a (PU-ST), 3a (FaF-LC), 4a ( Xen-[assumed] endgame)
4
The chapter number, based on which section it is in. (Forth chapter in section)
a
Map letter. All maps are labeled alphabetically, no matter how many maps in the chapter there are.

However, I doubt that since the devs should be following a rough similarity to the original game, most likely they wont stray too far from the original.
My opinion is one map.

I suspect that that the ‘c’ stands for compile, with either the Black Mesa team or the original HL1 developer team having used some sort of batch-based compilation tool to compile large numbers of maps at once.

I guess in new version of Xen in Black Mesa, each chapter has at least two maps.

However, developers may put multiple scenes in one map, using portals to connect them. For example, there’s only one map in Nihilanth in the original HL, but this map contains 4 different areas. So they will probably do the same as the original. This way can be used for small scenes, while large, complex scenes need to be cut to multiple maps for the optimization.

I remember Chon once said that there are about 14 maps in their version of Xen, which has been cut down several times in the progress of development, in their initial plan, there are more maps than the current version.

Actually, the ‘c’ stands for ‘chapter’ and the ‘a’ for ‘act’, so bm_c4a4a = Black Mesa - Chapter 4 Act 4 Map A.

[source]

Xen - 5 maps - c4a1x
Gonarch’s Lair - 3 Maps - c4a2x
Interloper - 5 Maps - c4a3x
Nihilanth - 1 Map - c4a4a
Endgame - 1 Map - c5a1a

This is where we stand currently. As always, potentially subject to change.

Posters above have already correctly outlined the way our naming convention works.

EDIT: Just to clarify, the first number is like “Act”. The second number is like “Chapter”. The final letter is the map name.

In the original game, I always felt that Xen was the weakest chapter. It was so short, the jarring switch to platforming detracted from the sense of bizarre otherworldliness of the alien dimension, and there was so little to see and explore before the player is thrown into a boss fight. It appears now that Xen will have a proper introduction, with much exploration and gameplay to allow the player to become accustomed to the rules of this new environment. Judging by the screenshots and other data, the Xen levels are so far beyond what I had expected that I honestly think the developers should call Black Mesa finished and release Xen as a new separate game. I’m sure that would be unlikely, and an unpopular choice, but it seems reasonable given the amount of time and effort Crowbar Collective has invested in this.

Founded in 2004, Leakfree.org became one of the first online communities dedicated to Valve’s Source engine development. It is more famously known for the formation of Black Mesa: Source under the 'Leakfree Modification Team' handle in September 2004.