CLEO review
A focused script and plugin runtime for GTA and Bully modding.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
CLEO is an open-source scripting library and mod loader for players, modders and developers working with supported Grand Theft Auto games and Bully. It runs custom scripts from a dedicated CLEO directory, supports custom missions and game features, and can be removed without modifying the original game files. Supported releases cover GTA III, GTA Vice City, GTA San Andreas, GTA IV, Bully, GTA: The Trilogy - The Definitive Edition, re3, reVC, GTA Liberty City Stories and GTA Vice City Stories, with support spanning Windows PC, iOS, PSP and PS2 environments.
Its main strength is the range of scripting options within a focused mod-loading model. CLEO includes scripting opcodes and runtime extensions, while plugin support adds commands and functionality. CLEO Redux extends the ecosystem to JavaScript and TypeScript, and SDK resources support plugin developers. That combination gives players access to custom gameplay content while giving developers several ways to extend the runtime. The dedicated installation directory also keeps scripts separate from original game files, which supports a removable setup.
CLEO is most suitable for users who already know which game and release they want to modify, because it is a family of related releases rather than one uniform loader. Capabilities and supported games vary by version, and the Windows, iOS, PSP and PS2 environments do not represent one identical feature set. Choose CLEO for script-based GTA or Bully modding, plugin development, and JavaScript or TypeScript work through CLEO Redux. Users seeking one consistent loader across every listed platform, or a tool centered on mod types beyond scripts and plugins, should consider a different category fit.
CLEO pros and cons
- Where it wins
- Runs custom scripts, missions and game features in supported titles
- Supports plugins, runtime extensions, and additional scripting commands
- Can be removed without modifying original game files
- Where it doesn't
- Capabilities vary across CLEO releases and supported games
- Focused on script and plugin modding rather than a broad mod toolkit
- Platform support spans different Windows, mobile and console environments
CLEO fact sheet, pricing and score →
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
Last updated · How we research and update