idk how much the devs of unmodded teeworlds care about enforcing this for 0.6 these days, but they were very particular about only vanilla servers being allowed to broadcast themselves as being on "DM", "TDM" and "CTF" modes
pretty sure it should be possible to compile a 0.6.5 server without the change that broke compatibility with all other 0.6 stuff
TBH, might be a good idea for somebody to make available (effectively) vanilla server binaries that do that, so less programmer-minded people can set up classic CTF and DM servers without having to learn what gcc/g++ are or figuring out how to set up bam