Could this return script actually work?

What exactly are you trying to return, and why return anyway? All the returns you have there are pointless. And even without return this script doesn't work.

return is used in functions which are used to process a value and return another. It is also used to cut a statement or loop short.

Here's an example of a function with return:

--Read game.Players.PlayerAdded first!

function getId(user) -- In the function we decide to refer to the Player instance as "user"
    id = user.UserId --We make this variable that gets the player's UserId
    return id --The variable we got above returns to the event function.
    --This means that, all lines which are inside the event function and which are after getId below now know a new variable: id.
end

game.Players.PlayerAdded:connect(function(player)
    getId(player) -- The Player instance that was added is taken for processing at the function
    print(id .. " has joined the server") -- The userid that joined gets printed.
    --Note that in some cases where you want an interger/number to be a string you must use tostring(number).
    --For reasons i don't know the script works without it.
end)

Here's an example ofreturn used as an interruption:

--Back in my early days on Roblox this is just what follower NPCs were.
repeat
--Suppose we have script on here that finds closest player and sets a global variable used below
    repeat
        if player == nil then return end -- The repeat loop ends abnormally if we have no player or his character
        if player.Character == nil then return end
        script.Parent:MoveTo(player.Character.Torso.Position)
        wait(0.07)
    until not (player and player.Character) --The repeat loop ends normally on this case
until false --This makes a repeat loop endless, provided there is no return for this one

Here's your script fixed (which doesn't need return as anything):

function round()
    local minigames = game.Lightning:GetChildren()        
    local map = minigames[number]
    local number = math.random(1, #minigames)
    local spawns = map.Spawns.GetChildren()
    local pointbrick = map.PointBrick
    for intermission = 25,1,-1 do
        game.Workspace.Timer.Value = "Intermission: "..intermission

    end
    game.Workspace.Timer.Value = "The game will start shortly."
    wait(3)
    game.Workspace.Timer.Value = "Choosing Minigame..."
    wait(3)
    game.Workspace.Timer.Value = "Minigame: "..map.Name
    wait(3)
    game.Workspace.Timer.Value = "Loading Minigame..."
    wait(3)
    mapModel = map:clone()
    mapModel.Parent = Workspace
    game.Workspace.Timer.Value = "Teleporting players..."
    wait(1)   
    for _, player in pairs(game.Players:GetPlayers()) do
        local character = player.Character
        local randomSpawn = spawns[math.random(#spawns)] -- EDIT
        if character then
            character:MoveTo(randomSpawn.Position) -- EDIT
         end
    end
    wait(1)
    for readySetGo = 3,1,-1
        game.Workspace.Timer.Value = readySetGo
        wait(1)
    end
    game.Workspace.Timer.Value = "Go!"
    for timer = 150,1,-1 do
        if not pointbrick then --Someone took the brick? End!
        --Make sure the pointbrick itself makes sure to remove when a player touches it.
                game.Workspace.Timer.Value = "Game over!" 
                mapModel:Destroy() --Remove() sets parent to nil and the mapModel can be referred to again. Destroy() will remove it completely, as you will never want to refer to it again.. Helps for later performance.
                wait(3)
        timer = 0 -- Make this the last loop, it's all over
    else
        game.Workspace.Timer.Value = "Time left: "..timer -- Not done yet? Then keep counting, i guess.
        wait(1) --Wait before the next second counting
        end
    end
    if pointbrick then
        game.Workspace.Timer.Value = "Nobody won. Too bad."
        mapModel:Destroy()
        wait(3)
    else
        game.Workspace.Timer.Value = "Game over! Winners get __ points!"
        mapModel:Destroy()
        wait(3)
     end
end

--The script you had here was removed on purpose. The main script cannot multitask like that so you'll have to give the pointbrick something to do.

I hope i helped with both the script and understanding return.

So I saw the answer. But you do realize that the game is a minigame place and that it will actually go like this?

function round()
    local minigames = game.Lightning:GetChildren()        
    local map = minigames[number]
    local number = math.random(1, #minigames)
    local spawns = map.Spawns.GetChildren()
    local pointbrick = map.PointBrick
    for intermission = 25,1,-1 do
        game.Workspace.Timer.Value = "Intermission: "..intermission

    end
    game.Workspace.Timer.Value = "The game will start shortly."
    wait(3)
    game.Workspace.Timer.Value = "Choosing Minigame..."
    wait(3)
    game.Workspace.Timer.Value = "Minigame: "..map.Name
    wait(3)
    game.Workspace.Timer.Value = "Loading Minigame..."
    wait(3)
    mapModel = map:clone()
    mapModel.Parent = Workspace
    game.Workspace.Timer.Value = "Teleporting players..."
    wait(1)   
    for _, player in pairs(game.Players:GetPlayers()) do
        local character = player.Character
        local randomSpawn = spawns[math.random(#spawns)] -- EDIT
        if character then
            character:MoveTo(randomSpawn.Position) -- EDIT
         end
    end
    wait(1)
    for readySetGo = 3,1,-1
        game.Workspace.Timer.Value = readySetGo
        wait(1)
    end
    game.Workspace.Timer.Value = "Go!"
    for timer = 150,1,-1 do
        if not pointbrick then --Someone took the brick? End!
        --Make sure the pointbrick itself makes sure to remove when a player touches it.
                game.Workspace.Timer.Value = "Game over!" 
                mapModel:Destroy() --Remove() sets parent to nil and the mapModel can be referred to again. Destroy() will remove it completely, as you will never want to refer to it again.. Helps for later performance.
                wait(3)
        timer = 0 -- Make this the last loop, it's all over
    else
        game.Workspace.Timer.Value = "Time left: "..timer -- Not done yet? Then keep counting, i guess.
        wait(1) --Wait before the next second counting
        end
    end
    if pointbrick then
        game.Workspace.Timer.Value = "Nobody won. Too bad."
        mapModel:Destroy()
        wait(3)
    else
        game.Workspace.Timer.Value = "Game over! Winners get __ points!"
        mapModel:Destroy()
        wait(3)
     end
end

while true do
    wait(1)
    round()
end