Checkpoints

Lesson 16 of 18 in Coddy's Roblox Game: Endless Tower course.

Falling to your death on stage 5 and starting from the bottom is harsh. With checkpoints, a player who dies starts again on the last stage they reached, which Stage already knows.

Every new character fires the player's CharacterAdded. Roblox places it on a spawn first, so wait a moment, then move it:

player.CharacterAdded:Connect(function(character)
	task.wait()
	local checkpoint = towerStages[stage.Value]
	if checkpoint then
		character:PivotTo(checkpoint.Start.CFrame + Vector3.new(0, 4, 0))
	end
end)

Before a player reaches any stage, towerStages[0] is nil, so they spawn in the lobby as usual. Winners are back in the lobby and should stay there.

The lava changes one thing. A stage it has covered is no checkpoint: a player put back there dies again at once, over and over, until the lava passes the next stage. Compare the stage's Start with the top of the lava, and leave a player whose checkpoint is under it in the lobby until the next round:

local covered = checkpoint and lava and checkpoint.Start.Position.Y < lava.Position.Y + lava.Size.Y / 2

Challenge

Hard

In PlayerAdded, after making the leaderstats, connect the player's CharacterAdded. Wait a moment with task.wait(), then, if towerStages[stage.Value] exists, the lava has not covered its Start, and the player has not finished this round, move the character to 4 studs above that stage's Start.

Press Play, climb a stage, and jump off. Then stay on it until the lava comes. Then Check.

Try it yourself

local Players = game:GetService("Players")
local ServerStorage = game:GetService("ServerStorage")
local CollectionService = game:GetService("CollectionService")
local RunService = game:GetService("RunService")
local TweenService = game:GetService("TweenService")
local Settings = require(game.ReplicatedStorage.Settings)

local stages = ServerStorage.Stages
local lobbySpawn = workspace.Lobby.SpawnLocation
local tower = nil
local towerStages = {}
local lava = nil
local finished = {}

print("Each tower has " .. Settings.StageCount .. " stages")

-- Every player gets Wins and Stage on the leaderboard
Players.PlayerAdded:Connect(function(player)
	local leaderstats = Instance.new("Folder")
	leaderstats.Name = "leaderstats"
	leaderstats.Parent = player

	local wins = Instance.new("IntValue")
	wins.Name = "Wins"
	wins.Parent = leaderstats

	local stage = Instance.new("IntValue")
	stage.Name = "Stage"
	stage.Parent = leaderstats
end)

-- The board in the lobby
local gui = Instance.new("SurfaceGui")
gui.Parent = workspace.Lobby.Board

local boardLabel = Instance.new("TextLabel")
boardLabel.Name = "Status"
boardLabel.Size = UDim2.fromScale(1, 1)
boardLabel.BackgroundColor3 = Color3.fromRGB(25, 25, 35)
boardLabel.TextColor3 = Color3.fromRGB(255, 255, 255)
boardLabel.TextScaled = true
boardLabel.Text = "Endless Tower"
boardLabel.Parent = gui

local function setBoard(text)
	boardLabel.Text = text
end

-- Anything tagged Kill ends a life
local function killOnTouch(hit)
	local humanoid = hit.Parent:FindFirstChild("Humanoid")
	if humanoid then
		humanoid.Health = 0
	end
end

-- A vanishing step fades soon after someone lands on it, then comes back
local function makeVanish(part)
	part.Touched:Connect(function(hit)
		if part:GetAttribute("Gone") or not hit.Parent:FindFirstChild("Humanoid") then
			return
		end
		part:SetAttribute("Gone", true)
		task.wait(Settings.VanishDelay)
		part.Transparency = 0.8
		part.CanCollide = false
		task.wait(Settings.VanishTime)
		part.Transparency = 0
		part.CanCollide = true
		part:SetAttribute("Gone", nil)
	end)
end

-- A laser slides to its Slide offset and back, forever
local function makeSlide(part)
	local info = TweenInfo.new(Settings.SlideTime, Enum.EasingStyle.Linear, Enum.EasingDirection.InOut, -1, true)
	local goal = { Position = part.Position + part:GetAttribute("Slide") }
	TweenService:Create(part, info, goal):Play()
end

-- A bounce pad throws whoever lands on it up into the air
local function bounce(hit)
	local root = hit.Parent:FindFirstChild("HumanoidRootPart")
	if root then
		root.AssemblyLinearVelocity = Vector3.new(0, Settings.BouncePower, 0)
	end
end

-- Spinners turn a little every frame
RunService.Heartbeat:Connect(function(dt)
	for _, spinner in CollectionService:GetTagged("Spinner") do
		if spinner:IsDescendantOf(workspace) then
			spinner:PivotTo(spinner:GetPivot() * CFrame.Angles(0, math.rad(Settings.SpinSpeed) * dt, 0))
		end
	end
end)

-- Turn on every obstacle in a stage, by its tags
local function setupStage(stage, index)
	for _, part in stage:GetDescendants() do
		if part:HasTag("Kill") then
			part.Touched:Connect(killOnTouch)
		end
		if part:HasTag("Vanish") then
			makeVanish(part)
		end
		if part:HasTag("Conveyor") then
			part.AssemblyLinearVelocity = part.CFrame.LookVector * Settings.BeltSpeed
		end
		if part:HasTag("Slider") then
			makeSlide(part)
		end
		if part:HasTag("Bounce") then
			part.Touched:Connect(bounce)
		end
	end
	-- reaching a stage's Start counts on the leaderboard
	stage.Start.Touched:Connect(function(hit)
		local player = Players:GetPlayerFromCharacter(hit.Parent)
		if player and player.leaderstats.Stage.Value < index then
			player.leaderstats.Stage.Value = index
		end
	end)
end

-- Any stage, at random
local function pickStage()
	local all = stages:GetChildren()
	return all[math.random(1, #all)]
end

-- Put a copy of a model on top of the tower; returns the copy and the new top
local function stack(template, bottom)
	local copy = template:Clone()
	local box, size = copy:GetBoundingBox()
	local lift = bottom - (box.Position.Y - size.Y / 2)
	copy:PivotTo(copy:GetPivot() + Vector3.new(0, lift, 0))
	copy.Parent = tower
	return copy, bottom + size.Y
end

-- The top of the tower: a win, and back to the lobby
local function reachTop(hit)
	local player = Players:GetPlayerFromCharacter(hit.Parent)
	if not player or finished[player] then
		return
	end
	finished[player] = true
	player.leaderstats.Wins.Value += 1
	print(player.Name .. " reached the top")
	hit.Parent:PivotTo(lobbySpawn.CFrame + Vector3.new(0, 4, 0))
end

-- Build a new random tower, bottom up
local function buildTower()
	tower = Instance.new("Model")
	tower.Name = "Tower"
	tower.Parent = workspace
	towerStages = {}
	local top = 0
	for i = 1, Settings.StageCount do
		local stage, newTop = stack(pickStage(), top)
		top = newTop
		setupStage(stage, i)
		towerStages[i] = stage
	end
	local finish = stack(ServerStorage.Finish, top)
	finish.FinishPad.Touched:Connect(reachTop)
	return top
end

-- Lava rises from the ground to just under the top of the tower
local function startLava(top)
	lava = Instance.new("Part")
	lava.Name = "Lava"
	lava.Anchored = true
	lava.CanCollide = false
	lava.Size = Vector3.new(30, 2, 30)
	lava.Position = Vector3.new(0, -2, 0)
	lava.Color = Color3.fromRGB(255, 90, 20)
	lava.Material = Enum.Material.Neon
	lava.Parent = workspace
	lava.Touched:Connect(killOnTouch)
	local info = TweenInfo.new(top / Settings.LavaSpeed, Enum.EasingStyle.Linear, Enum.EasingDirection.InOut, 0, false, Settings.LavaDelay)
	TweenService:Create(lava, info, { Position = Vector3.new(0, top - 2, 0) }):Play()
end

local function startRound()
	finished = {}
	for _, player in Players:GetPlayers() do
		player.leaderstats.Stage.Value = 0
	end
	local top = buildTower()
	startLava(top)
	for _, player in Players:GetPlayers() do
		if player.Character then
			player.Character:PivotTo(towerStages[1].Start.CFrame + Vector3.new(0, 4, 0))
		end
	end
end

local function endRound()
	for _, player in Players:GetPlayers() do
		if player.Character and not finished[player] then
			player.Character:PivotTo(lobbySpawn.CFrame + Vector3.new(0, 4, 0))
		end
		player.leaderstats.Stage.Value = 0
	end
	tower:Destroy()
	lava:Destroy()
	towerStages = {}
end

-- The round loop
while true do
	for i = Settings.Intermission, 1, -1 do
		setBoard("Next tower in " .. i)
		task.wait(1)
	end
	startRound()
	for i = Settings.RoundLength, 1, -1 do
		setBoard("Climb! " .. i .. " seconds left")
		task.wait(1)
	end
	endRound()
end