How do I write a complete Roblox Lua ServerScript for ServerScriptService that increases each alive player's Humanoid WalkSpeed by 1 every second and supports character respawning without errors?

Question

AskAI Engine · Accepted Answer

This ServerScriptService script safely increases each player's Humanoid.WalkSpeed by 1 every second while they are alive. It handles character respawning by listening to CharacterAdded and re-binding to the new Humanoid instance. It also prevents common errors by checking for missing characters, missing Humanoids, and by cleaning up connections when players leave. Paste this into a Script placed in ServerScriptService and it will run automatically.Roblox ServerScriptService Script (ServerScriptService)Instructions: Create a Script in ServerScriptService, then replace its contents with the code below.ServerScriptService Script:-- ServerScriptService Script
-- Increases each alive player's Humanoid.WalkSpeed by 1 every second.
-- Works with character respawning and avoids errors.

local Players = game:GetService("Players")

-- How often to apply the speed increase (seconds)
local INTERVAL = 1

-- How much to increase WalkSpeed each tick
local SPEED_INCREMENT = 1

-- Track per-player state so we can stop loops when they leave
local playerState = {}

local function getHumanoidFromCharacter(character)
	if not character then return nil end
	local humanoid = character:FindFirstChildOfClass("Humanoid")
	return humanoid
end

local function startSpeedLoop(player)
	-- If a loop already exists (shouldn't, but safe), stop it first
	if playerState[player] and playerState[player].running then
		playerState[player].running = false
	end

playerState[player] = playerState[player] or {}
	playerState[player].running = true

-- Each loop iteration uses the latest humanoid reference
	-- by re-checking the character each tick.
	local function tick()
		while playerState[player] and playerState[player].running do
			local character = player.Character
			local humanoid = getHumanoidFromCharacter(character)
			if humanoid and humanoid.Parent then
				-- Only apply while alive
				if humanoid.Health > 0 then
					-- Ensure WalkSpeed exists before setting
					local current = humanoid.WalkSpeed
					if typeof(current) == "number" then
						humanoid.WalkSpeed = current + SPEED_INCREMENT
					end
				end
			end
			task.wait(INTERVAL)
		end
	end

-- Run in a separate thread so CharacterAdded can still work
	task.spawn(tick)
end

local function stopSpeedLoop(player)
	if playerState[player] then
		playerState[player].running = false
	end
end

local function onCharacterAdded(player, character)
	-- When a new character spawns, the loop will automatically
	-- pick up the new Humanoid on the next tick.
	-- This function exists to ensure we handle respawns cleanly.
	-- We also do a quick early check to reduce time-to-effect.
	local humanoid = getHumanoidFromCharacter(character)
	if humanoid and humanoid.Health > 0 then
		-- Apply one immediate increment so respawn feels responsive.
		local current = humanoid.WalkSpeed
		if typeof(current) == "number" then
			humanoid.WalkSpeed = current + SPEED_INCREMENT
		end
	end
end

-- Connect player lifecycle
Players.PlayerAdded:Connect(function(player)
	-- Start the speed loop for this player
	startSpeedLoop(player)

-- Handle respawns
	player.CharacterAdded:Connect(function(character)
		onCharacterAdded(player, character)
	end)

-- If the character already exists (rare but possible), handle it
	if player.Character then
		onCharacterAdded(player, player.Character)
	end
end)

Players.PlayerRemoving:Connect(function(player)
	stopSpeedLoop(player)
	playerState[player] = nil
end)

-- Optional: handle already-present players if the script is added at runtime
for _, player in ipairs(Players:GetPlayers()) do
	startSpeedLoop(player)
	player.CharacterAdded:Connect(function(character)
		onCharacterAdded(player, character)
	end)
	if player.Character then
		onCharacterAdded(player, player.Character)
	end
end
Why this script won’t error on respawnCharacter respawning: The loop always reads player.Character each tick, so it naturally uses the newest Humanoid.Nil checks: It uses FindFirstChildOfClass("Humanoid") and verifies the humanoid exists and has a parent.Alive check: It only increases speed when humanoid.Health > 0.Cleanup: When the player leaves, running is set to false so the loop stops.Common customizationChange speed increment: Set SPEED_INCREMENT to a different number.Change frequency: Set INTERVAL to something like 0.5 for twice per second.Cap WalkSpeed: If you want a maximum, you can clamp before setting, for example: humanoid.WalkSpeed = math.min(current + SPEED_INCREMENT, MAX_SPEED).Quick cap example (optional)If you want to cap the speed, add these lines inside the alive check:local MAX_SPEED = 50
local current = humanoid.WalkSpeed
if typeof(current) == "number" then
	humanoid.WalkSpeed = math.min(current + SPEED_INCREMENT, MAX_SPEED)
end
If you tell me your desired WalkSpeed cap (or whether you want it to scale with level), I can adjust the script accordingly?

How do I write a complete Roblox Lua ServerScript for ServerScriptService that increases each alive player's Humanoid WalkSpeed by 1 every second and supports character respawning without errors?

🏆 Main Sources

Additional Sources