This project discovers, polls, and lists RTCW and Enemy Territory servers -- querying every master
it knows about (see master servers), collapsing detected
duplicates (see port padding), and running its own
UDP master on 27950 so servers can heartbeat straight to it even when the official one is
down.
RTCW and ET are both built on id Software's Quake III engine, which is also where their server
discovery protocol (getstatus/getservers/heartbeat -- the same one this
project's own master speaks) comes from. That happens to be the same protocol Quake 3 Arena and
OpenArena use, so once RTCW/ET support existed, tracking
those too came along mostly for free.
Source is on GitHub, and contact info is here if you run into anything.