Welcome to the official site of the CLEO library (or simply CLEO) - a hugely popular extensible plugin for the Grand Theft Auto games series by Rockstar Games, allowing the use of thousands of unique mods which change or expand the gameplay. There are different versions of CLEO made for GTA III, GTA Vice City and GTA San Andreas.



Using CLEO it's possible to add custom scripts written with Sanny Builder or another script editor to the game without starting a new game. Adding and removing a script is as easy as copying and deleting a file in the CLEO folder.

These third-party scripts are entirely user-made and are in no way supported by the developers of this library. While CLEO itself should work in a wide range of game installations, individual scripts are known to have their own compatibility restrictions and can not be guaranteed to work.

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CLEO 4 adds 100 useful scripting commands (opcodes) that make possible to work with external files, to change the game memory, to call exe functions with custom parameters and much more.

New opcodes were added in the fourth version to play audio streams, to format strings, to display custom texts on screen without using external text files (.fxt, .gxt). To assess all the achievements and use them in your scripts, install the latest version of the CLEO library.

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CLEO plugins are dynamic libraries having the .cleo extension. At startup, the CLEO library scans the CLEO folder for the files with that extension and tries to load them. If successful, the plugins begin to work and do what they were made for.

CLEO 4 allows to make new opcodes using sources of the CLEO SDK. The starter kit contains three examples of such plugins.

Plugins are installed in the same way as scripts.

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CLEO 4 is distributed in an archive. To install the library unpack the archive into the game directory.

CLEO 4 supports GTA San Andreas 1.0 US version. Downgrade your game if you have a different version.

CLEO requires an 'ASI Loader' installed to run which is provided with the release. The ASI Loader requires overwriting one original game file: vorbisFile.dll - be sure to make a backup of this file. No additional files are replaced, however the following files and folders are added:
- cleo\ (CLEO script directory)
- cleo\FileSystemOperations.cleo (file system plugin)
- cleo\IniFiles.cleo (INI config plugin)
- cleo\IntOperations.cleo (INT operations plugin)
- cleo\cleo_saves\ (CLEO save directory)
- cleo\cleo_text\ (CLEO text directory)
- cleo.asi (core library)
- bass.dll (audio engine library)
- vorbisHooked.dll (Silent's ASI Loader)

All plugins are optional, however they may be required by various CLEO scripts.

CLEO 4 for San Andreas needs the BASS.dll v2.4 to be installed. This dll file can be downloaded from the official site of Un4seen Developments Ltd.

Compatibility Mode

CLEO is continually being improved and extended over time. In very rare circumstances, some scripts written for CLEO 3 may not work while using CLEO 4. However, since CLEO 4.3 you are able to enable a 'legacy mode' to increase compatibility with CLEO 3 scripts by naming them with the extension .cs3. CLEO 4.3 will load .cs and scripts normally and load .cs3 scripts in CLEO 3 compatibility mode, in which certain small behaviours of the CLEO library will change to achieve better compatibility with that script. However, most CLEO 3 scripts will work without the need for compatibility mode being set as CLEO 4.3 also detects certain necessary CLEO 3 behaviours. Specifically, scripts which use the uninitialized storage data after a SCM function call to work.


The author and original developer of the CLEO library is Seemann.

Alien began development of CLEO 4, now continued by Deji.

The developers have no connection with Take 2 Interactive or Rockstar Games and have no liability for any negative consequences caused by using this product or any of the additional products included. Use it at your own risk.

CLEO 4.3 uses the ASI Loader by Silent.

More information about changes in version 4.3 and the CLEO library features can be found in the readme files which are installed along with CLEO and at this topic.

Thanks to:

CLEO for GTA 3 and GTA Vice City

The huge success of CLEO for San Andreas inspired Alien to port the library to GTA 3 and Vice City. Some features, such as custom CLEO saves storing variables and scripts state were cut off.

After Alien's retirement, the development slowed down until Silent issued a patch to the latest available version. Soon after that DK22Pac announced the next version of CLEO for GTA 3 and Vice City, written from scratch. It was never released, but ThirteenAG helped to finish his work and CLEO 2.0 for GTA 3 and VC is now available for download.

More information can be found on GTAForums.com.

The source code can be found on GitHub.