"Write me the most complex script for time"

I'm not sure what you mean by "the most complex script for time," but here's a script that demonstrates a digital clock system in Roblox using a SurfaceGui. This script updates the clock every second and displays the current time in hours, minutes, and seconds.

--lua
-- Server Script
local function createTimeLabel(parent)
    local label = Instance.new("TextLabel")
    label.Parent = parent
    label.Size = UDim2.new(1, 0, 1, 0)
    label.BackgroundTransparency = 1
    label.TextScaled = true
    label.Font = Enum.Font.SourceSansBold
    label.TextColor3 = Color3.new(1, 1, 1)
    return label
end

local function createClock(part)
    local surfaceGui = Instance.new("SurfaceGui", part)
    surfaceGui.Face = Enum.NormalId.Front
    surfaceGui.LightInfluence = 0
    surfaceGui.CanvasSize = Vector2.new(500, 500)
    local timeLabel = createTimeLabel(surfaceGui)
    return timeLabel
end

local clockPart = Instance.new("Part", workspace)
clockPart.Size = Vector3.new(10, 5, 1)
clockPart.Anchored = true
clockPart.CFrame = CFrame.new(0, 5, 0)
local clockLabel = createClock(clockPart)

while true do
    local currentTime = os.date("*t")
    local hours = string.format("d", currentTime.hour)
    local minutes = string.format("d", currentTime.min)
    local seconds = string.format("d", currentTime.sec)
    clockLabel.Text = hours .. ":" .. minutes .. ":" .. seconds
    task.wait(1)
end
--

This script creates a part in the workspace, adds a SurfaceGui to it, and updates the displayed time every second. The time is formatted as a digital clock with hours, minutes, and seconds.