How do you connect multiple game stats into a main lobby?

Using the official Roblox Api, you can get the number of players in several different places.

For example, if I wanted to check how many people were playing crossroads (place id 1818), I would go to the link https://www.roblox.com/games/getgameinstancesjson?placeId=1818&startindex=0. The text it shows is:

{
   "PlaceId":1818,
   "ShowShutdownAllButton":false,
   "Collection":[
      {
         "Capacity":8,
         "Ping":66,
         "Fps":59.974594,
         "ShowSlowGameMessage":false,
         "Guid":"8ad4c4b2-5c00-41f7-92f9-747b60382baa",
         "PlaceId":1818,
         "CurrentPlayers":[
            {
               "Id":0,
               "Username":"A Roblox Player",
               "Thumbnail":{
                  "AssetId":0,
                  "AssetHash":null,
                  "AssetTypeId":0,
                  "Url":"https://tr.rbxcdn.com/0f0a14eb846140dfc1f28870921b38d8/48/48/AvatarHeadshot/Png",
                  "IsFinal":true
               }
            },
            ...
         ],
         "UserCanJoin":true,
         "ShowShutdownButton":false,
         "JoinScript":"Roblox.GameLauncher.joinGameInstance(1818, \"8ad4c4b2-5c00-41f7-92f9-747b60382baa\")",
         "FriendsDescription":"",
         "FriendsMouseover":"",
         "PlayersCapacity":"7 of 8 players max"
      },
      ...
   ],
   "TotalCollectionSize":3
}

To go to the link with Roblox scripts, you can use

local HttpService = game:GetService("HttpService")
local PlaceId = 1818 -- Crossroads
local StartIndex = 0
local Link = string.format("https://www.rprxy.xyz/games/getgameinstancesjson?placeId=%s&startindex=%s", PlaceId, StartIndex)
local Data = HttpService:GetAsync(Link)
print(Data)

It will print the data in the output. But let's say that you want to turn it into a Lua table. You would, of course, use HttpService:JSONDecode. Let's add that to our script.

local HttpService = game:GetService("HttpService")
local PlaceId = 1818 -- Crossroads place id
local StartIndex = 0 -- Start at server #0
local Link = string.format("https://www.roblox.com/games/getgameinstancesjson?placeId=%s&startindex=%s", PlaceId, StartIndex) -- Set link with parameters
local Data = HttpService:GetAsync(Link) -- Get data from link
local DecodedData = HttpService:JSONDecode(Data) -- Decode the data
-- print(Data)

Count the number of people in the servers

local HttpService = game:GetService("HttpService")
local PlaceId = 1818 -- Crossroads place id
local StartIndex = 0 -- Start at server #0
local Link = string.format("https://www.roblox.com/games/getgameinstancesjson?placeId=%s&startindex=%s", PlaceId, StartIndex) -- Set link with parameters
local Data = HttpService:GetAsync(Link) -- Get data from link
local DecodedData = HttpService:JSONDecode(Data) -- Decode the data
local PlayerCount = 0
for Index, Server in pairs(DecodedData["Collection"]) do
    PlayerCount += #Server["CurrentPlayers"]
end

Notice this only returns the first ten servers. This problem can be easily solved by integrating a loop.

local HttpService = game:GetService("HttpService")
local PlaceId = 1818 -- Crossroads place id
local StartIndex = 0 -- Start at server #0
local Link = string.format("https://www.roblox.com/games/getgameinstancesjson?placeId=%s&startindex=%s", PlaceId, StartIndex) -- Set link with parameters
local Data = HttpService:GetAsync(Link) -- Get data from link
local DecodedData = HttpService:JSONDecode(Data) -- Decode the data

for Index, Server in pairs(DecodedData["Collection"]) do
    PlayerCount += #Server["CurrentPlayers"]
end

for NewStartIndex = 10, DecodedData["TotalCollectionSize"], 10 do
    Link = string.format("https://www.roblox.com/games/getgameinstancesjson?placeId=%s&startindex=%s", PlaceId, NewStartIndex)
    local NewData = HttpService:GetAsync(Link)
    local NewDecodedData = HttpService:JSONDecode(NewData)
    for Index, Server in pairs(NewDecodedData["Collection"]) do
        PlayerCount += #Server["CurrentPlayers"]
    end
end

print(PlayerCount)

Hope this works!