See Also : History of Crossfire

The open source code of Crossfire has been used by people, who wanted to create their own monsters, maps or skills .

Most are hosted on https://sourceforge.net .
When using the search input box there, it brings around 20 hits.
Unfortunately around half of the Crossfire related projects stopped submitting files after a short time,
indicating, that the Crossfire source code base is too large to work on as a single programmer.

1. Wograld : Started with version 1.9, too few developers, forum exists no more.
2. Deliantra : Bigworld split into two continents divided by sea.
3. CrossCiv : A galactic milieu for crossfire – whatever that is.
4. Crossfire-Extended : Pre-2008 Crossfire Server with extended maps.
5. Crossfire2000 : Server and Maps version 1.11.0, Clients v.1.0.y and 1.12.0 .

Wograld source code is hosted on sourceforge : https://sourceforge.net/p/wograld
It has a summary and a blog .
: link addresses on sourceforge

Cvs access did not work for me, since the source is set read-only. Using rsync, it needs then the rcs package installed, to extract it's `,v' archive files using `rcs co' , which is short for checkout.

Status : no current downloads, cvs archive access through rsync, difficulties with bugs in the old client crashing the server

Noteworthy the 9 Stupidities, however they have implemented these.

About the artwork : The monsters have a more humanoid face; many monsters, who just are usually one tile in size, are two tiles in size :

Deliantra is still up as of February 2018.

Noteworthy it's address to view Maps

CrossCiv is still up, people can connect as of February 2018.
CrossCiv code is hosted on sourceforge : https://sourceforge.net/p/galacticmilieu
It's wiki at sourceforge is explaining much.
The player needs to be a normal character that does not use magic or prayers to access the galactic milieu.
Otherwise, the character is send to a usual crossfire-style fantasy world, with an uncommon starting island map.
The client to connect to crossciv.no-ip.org needs to be v1.60.0 or newer, to play it fully functional.

The Crossfire Extended seems to be split into two projects on Sourceforge :

• Release that contains server and client
• Maps and Archetypes

The ChangeLog entries suggest, that they were forked already short time after the release of version 1.9.0 of crossfire.
It's main page says :

Contains old features that were loved (but were taken out of regular crossfire) weather generation etc.
A crossfire from another age.
If you like the pre 2008 CF, here it is with lots and lots and lots more maps!
More archtypes and items.
Including full new building sets: germanic, candy-kingdomish/russian, japanese, middle east.

The source code tarball includes pre-build executables for 64bit kernels.
https://sourceforge.net/projects/crossfireextendedrelease

https://sourceforge.net/projects/cfextended

It says not much there :

Rehash of crossfire for newer OS

Whatever that means …

Url : https://sourceforge.net/projects/crossfire2000