--- Once again my PC shut off at home so I can't test this... oh well at least I can type ideas down.
local Player = game.Players.LocalPlayer
local Char = Player.Character
---Services
local InputService = game:GetService("UserInputService")
---Deboucnes
local RevealDB = false
--Highlightstats
local HighlightDuration = 5    
local HighlightColor = Color3.New(0,0,0) -- basic white color    
    
local function RevealAllEntities()
    RevealDB = true
   local Highlights = {}
    for i, NewChar in pairs(game.WorkSpace:GetChildren()) do
    if NewChar:FindFirstChild("Humanoid") ~= nil and NewChar.Name ~= Char.Name then
        if NewChar.Humanoid.Health > 0 then  -- if statements to see if they should be detected
           local Highlight = Instance.new("Highlight",NewChar)
               Highlight.OutlineColor = HighlightColor
                    table.Insert(HighlightedChars, Highlight)   
               NewChar.Humanoid.Died:Connect(function() 
                    if Highlight.Parent ~= nil then Highlight:Destroy() end
                    end)
                
        end
    end
    
        task.wait(HighlightDuration)
        if #Highlights > 0 then
            for i, Highlight in Pairs(Highlights) do
              if Highlight.Parent ~= nil then Highlight:Destroy() end
                end
            end
        RevealDB = false
    end
    
    -- tbh I'd prefer making it a client event but here's a basic input use for it
    InputService.InputBegan:Connect(function(input, GameProcessed)
    if not GameProcessed then
       if input.Keycode == Enum.Keycode.F and RevealDB == false then
         RevealAllEntities()
       end
    end
end)