Specificities of the Lua implementation in Civ5

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This page is a part of the Lua and UI Reference.

The Civ5 implementation is based on Lua 5.1.4. However it has been modified, mainly for sandboxing purposes.

Missing elements

Those items do not exist in the Civ5 implmentation of Lua. See Lua Reference#Index if you want to learn what they are for.

Missing globals

  • __G

Missing functions

Use include instead of the load*, module and require functions. See the next section for more informations.

  • getfenv
  • load
  • loadfile
  • loadstring
  • module
  • require
  • setfenv
  • setfenv

Missing objects

For I/O, use the methods from UI and Modding instead.

  • file
  • io
  • package
  • os: it still exists but only contains the clock, date, time and difftime functions.
  • debug: fortunately it has been added by Firaxis in May 2012. See Lua Debugging (Civ5)


Instead of the usual functions for loading and requiring a Lua file from another, Civ5 provides a custom function to do so: include.


table(int => string) include(string file, bool useRegex = false)

  • file: the name of the file, with or without extension. It can also be a local path starting from "Assets\UI" (see examples). Finally, if useRegex is true, it can be a regular expression where the % character is used instead of \.
  • useRegex: when true, the file argument will be treated as a regular expression.
  • returned value: an array that contains all the loaded files (a single one usually, many files if you did use a regular expression).
include("Ingame\\CityBannerManager.lua") -- loads Assets/UI/Ingame/CityBannerManager.lua
include("CityBanner%w+.lua", true) -- loads all files starting with "CityBanner" and ending with ".lua".

-- Loads all "*Popup.lua" files in Assets/UI/Ingame/PopupsGeneric. 
-- Then we print a statement for each one of the included files.
local files = include("InGame\\PopupsGeneric\\%w+Popup.lua", true);
for i, v in ipairs(files) do
    print("Loaded Popup - "..v);


  • Only the files that have been imported into the VFS may be included.
  • Usually only the first eight characters are checked. This is likely only true if you do not specify the path. This means that if you registered two files named MapScannerA.lua and MapScannerB.lua, using include("MapScannerA") could either load the A file or the B file!
  • When called in reaction to an UI event, include can silently fail. For example if you use it inside a function and this function is called in reaction to a click on a button, include will report it has been successful but the globals declared in the included file will not be included. This does not happen if you call this function after a Context update or at the time the mod is loaded.