Motivation for this change

hhexen is a modern engine for playing Hexen:

[Hacked Hexen] based on K.Robillard's Linux Hexen engine, is finally being finished after Dan left it in limbo for a while. New stuff includes midi, screenshots, bug-fixes, transparent maps, and extensive C fixes allowing for OS and CPU portability.

It offers a substantial visual upgrade over some existing Hexen engines in nixpkgs.

chocolate-hexen:

hhexen:

This is a different engine from than the one mentioned in #75468.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.