How USBX runs your code

Side by side: a ferry ticket

Here is a button that sails the player to a secret island for 15 tokens, written both ways.

-- LocalScript, inside the button
local remote = game.ReplicatedStorage:WaitForChild("SailToIsland")

script.Parent.Activated:Connect(function()
  remote:FireServer()
end)

-- Script, on the server
local remote = game.ReplicatedStorage.SailToIsland

remote.OnServerEvent:Connect(function(player)
  -- A cheater can fire this any time, so check everything.
  local tokens = player.leaderstats.Tokens
  if tokens.Value >= 15 and player.Character then
    tokens.Value -= 15
    player.Character:PivotTo(CFrame.new(0, 50, 500))
  end
end)

-- Script, on the server
local ferry = ui.mount(player, {
  kind = "panel", anchor = "bottom",
  children = {
    { kind = "button", id = "sail", text = "Sail: 15 tokens" },
  },
})

ferry.clicked:connect(function(who, id)
  if id == "sail" and tokens:get(who) >= 15 then
    tokens:increment(who, -15)
    who:teleport(math3d.vector3.new(0, 50, 500))
  end
end)

How players reach your scripts

What happens when a player steps on lava.

1. 1
   Input arrives

   The player walks forward.

2. 2
   The player touches lava

   They are now touching a part tagged "Lava".

3. 3
   Your scripts run

   touched fires, and your script calls player:kill().

Talking between scripts