how to make a value for all players?

This can be done very easily by creating a single value and adding to the value every time an egg is hatched.

local EggsHatched = workspace.Values.EggsHatched -- Assuming the value "EggsHatched" is in workspace inside a folder called Values.

-- Run this code on the server below every time an egg is hatched.
EggsHatched += 1

If you want to read the value on the client put the NumberValue inside a place accessable to the client, such as ReplicatedStorage or Workspace.

When checking the clicks on the client you would need a remote event to communicate with the server about adding to the value. Read more about remote events here.

If you need this value to be saved i would suggest looking into the DataStoreService.

You can add a number value and place it somewhere like Players, then add a number value in players when they join, and then when the number value in Players updates, you change all the players' number values to the value of the number in Players.

local Players = game:GetService("Players")
local NumberValue = Players:WaitForChild(YourNumberValue)

Players.PlayerAdded:Connect(function(Player)
    if Player:FindFirstChild(ValueName) then
        Player:FindFirstChild(ValueName):Destroy()
    end

    local Value = Instance.new("NumberValue")
    Value.Name = ValueName
    Value.Value = NumberValue.Value
    Value.Parent = Player

    NumberValue:GetPropertyChanged:Connect(function()
        Value.Value = NumberValue.Value
    end)
end)