This page is just a reference of all the known Steam APIs, I do not know how they work. Please do not email me with questions.
GETGetGameMapsPlaytime
https://api.steampowered.com/ICSGOServers_730/GetGameMapsPlaytime/v1/
NameValueTypeRequiredDescription
string Yes What recent interval is requested, possible values: day, week, month
string Yes What game mode is requested, possible values: competitive, casual
string Yes What maps are requested, possible values: operation
GETGetGameServersStatus
https://api.steampowered.com/ICSGOServers_730/GetGameServersStatus/v1/
UNDOCUMENTEDGetLeaderboardEntries
https://api.steampowered.com/ICSGOServers_730/GetLeaderboardEntries/v1/
NameValueTypeRequiredDescription
string Yes Name of the leaderboard, must start with official_leaderboard_premier_<season>, optionally followed by _<country>, e.g. official_leaderboard_premier_season3 or official_leaderboard_premier_season2_europe
UNDOCUMENTEDGetMonthlyPlayerCount
https://api.steampowered.com/ICSGOServers_730/GetMonthlyPlayerCount/v1/