steamcli server — the desktop client's Game Servers dialog, on the command line.
steamcli server browse 730 --not-empty --secure
steamcli server info 10.0.0.5:27015 --players --rules
steamcli server favorites --refresh
steamcli server add 10.0.0.5:27015
steamcli server lan
steamcli server connect 10.0.0.5:27015- browse searches Valve's master list with a typed filter (map, gametype, name, version, secure, dedicated, not-empty…). Any APPID accepts a game name.
- info queries a server directly over A2S — status, scoreboard and rules — with no API key.
- favorites and history read and write Steam's own file, so changes show up in the client. Writes are atomic, preserve everything they do not model, and keep a backup. Close Steam first; the commands warn when it is running.
- lan broadcasts a query and reports whoever answers.
Uses rumblefrog/go-a2s (MIT, zero transitive dependencies) rather than reimplementing the protocol. A panic in that library, triggered by a malformed reply from a real server, is contained so one bad host cannot take down a listing.