Few days ago Take-Two Interactive warned the developer of the OpenIV modding tool which allows players to mod Rockstar titles like Grand Theft Auto V, Max Payne 3.
However, due to the negative reaction from the studio’s playerbase and modding community, Rockstar Games released an official statement defending their games’ modders and thanked players and modders for showcasing their passion towards the developer’s titles through continuous mods and support.
Rockstar Games believes in reasonable fan creativity, and, in particular, wants creators to showcase their passion for our games. After discussions with Take-Two, Take-Two has agreed that it generally will not take legal action against third-party projects involving Rockstar’s PC games that are single-player, non-commercial, and respect the intellectual property (IP) rights of third parties. This does not apply to (i) multiplayer or online services; (ii) tools, files, libraries, or functions that could be used to impact multiplayer or online services, or (iii) use or importation of other IP (including other Rockstar IP) in the project. This is not a license, and it does not constitute endorsement, approval, or authorization of any third-party project. Take-Two reserves the right to object to any third-party project, or to revise, revoke and/or withdraw this statement at any time in their own discretion. This statement does not constitute a waiver of any rights that Take-Two may have with respect to third-party projects.
So Mod that only involving Rockstar’s PC games that are single-player, non-commercial, and respect the intellectual property rights of third parties will not get legal action.