Garry's Mod. Simple, yet safe spawn protection system. Scripted for beginner challenges (https://facepunch.com/showthread.php?t=1487912).

simple_spawn_protection.lua

-- This code is for begginers; I have intentionally left out lots of things such as auto-refresh compatibility...
if ( !SERVER ) then
  -- This script is mean to be executed/opened on the serverside!
  ErrorNoHalt( "Not serverside" ) -- Tell an admin it is not run from environment where it is expected as.
  return -- Exit/terminate a script.
end

-- ConVars to manage the spawn protection system:
local sv_spawnprotection = CreateConVar( "sv_spawnprotection", "1", { FCVAR_ARCHIVE, FCVAR_NOTIFY }, "Determines whether simple spawn protection is enabled or disabled" )
local sv_spawnprotection_delay = CreateConVar( "sv_spawnprotection_delay", "8", { FCVAR_ARCHIVE, FCVAR_NOTIFY }, "Determines how long should spawn protection last in seconds after a player has spawned" )

--[[-----------------------------------------------
GM:PlayerSpawn(Player)
AVAILABILITY: Server
DESCRIPTION: Called whenever a player spawned.
ARGUMENTS:
  (1) Player, ply: The player who spawned.
-----------------------------------------------]]
hook.Add( "PlayerSpawn", "SimpleSpawnProtection.PlayerSpawn", function( ply )
  if ( !sv_spawnprotection:GetBool() ) then
    return -- Spawn protection is disabled.
  end
  -- Spawn protection is enabled.
  ply:GodEnable() -- Enable god mode on the player.
  timer.Simple( sv_spawnprotection_delay:GetInt(), function()
    -- Timer will run this function only once (in background), automatically after sv_spawnprotection_delay:GetInt() seconds have passed (by default, after 8s).
    if ( IsValid( ply ) ) then -- We must ensure a player object remained valid after delay (it would be invalid and cause script errors if a player have disconnected from the server)..
      ply:GodDisable() -- Disable god mode on the player.
    end
  end )
end )