I'm the maintainer for the slackware build script for 0ad. I've just updated the script for 0.27.0 and there is an extra dependency of rust-opt. It's been a while since the last update, and there was the move to gitea and change of forum logins, so I can't remember how to update https://gitea.wildfiregames.com/0ad/0ad/wiki/BuildInstructions
the slackware 14.2 instructions are now obsolete, and the 15.0 instructions need updating for the change. The new build scripts should be available at https://slackbuilds.org/repository/15.0/games/0ad/ and at https://slackbuilds.org/repository/15.0/games/0ad-data/ by 20th april 2025 (the public push is on weekends, so my update missed this one)
Any pointers would be helpful. my email address is also on the 0ad.info and 0ad-data.info files.