If you run a CS2 community server, a Minecraft network, or any game backend, the question "is it down right now" arrives in your Discord before it arrives in your inbox. Players check faster than your monitoring does, unless your monitoring checks like a player.
Pinging the host is not enough
A game server can be "up" at the network layer and broken in every way that matters. The machine responds to ICMP while the game process crashed twenty minutes ago. Or the process runs but stopped answering queries, so the server browser shows it as dead while your uptime check stays green.
The check that matters is the query protocol: the same request the server browser or client makes when listing the server. For Source-engine games like CS2 that is the A2S query over UDP. If the server answers the query, players can see and join it. If not, it is down for them regardless of what ping says.
What to actually watch
The game query. Monitor the A2S response on the server port, not just the host. This catches crashed processes, hung servers and misconfigured query ports.
The host underneath. An agent on the box watching CPU, memory and disk catches the slow deaths: a log volume filling up, a memory leak that OOM-kills the process at 3 AM, a runaway plugin eating the CPU during match start.
The map tick and player count. Sudden drops tell you about problems a simple up/down check misses, like a broken update kicking everyone or a workshop map failing to load.
Steam and upstream. Sometimes the server is fine and Steam's session servers are the problem. Knowing which half is broken decides whether you restart anything or just post "not us, Steam is down" and wait.
Alerts that reach the admins
A down alert that lands in an email inbox checked once a day is useless for a game community. Route it where the admins live: Discord or Slack for most teams, SMS or a call for the ones who pay for the box. The faster the alert lands, the fewer "server dead?" messages you read the next morning.
Set expectations on the status page
Community servers live and die on trust. A small status page showing the server's uptime history and current incidents does more for retention than another admin announcement. Players forgive downtime. They do not forgive silence.