We recently released the official tool kit for RAGE -- the same tools used to create RAGE and it's DLC, The Scorchers. From the game's world building tool, idStudio, to game maps and assets, the kit provides everything you need to get started with modding the first-ever idTech 5 title.

We encourage you to use these forums to discuss your projects and learn more about the tool kit.

Before you start downloading the hefty 35+ GB file, the RAGE team has provided some documents to read. As described in the welcome document, these tools provided are complex and aimed towards "technically sophisticated and adventurous" modders.

http://cdnstatic.gamesas.com/bethblog.com/wp-content/uploads/2013/02/RAGE%20Tool%20Kit%20Welcome.pdf
http://cdnstatic.gamesas.com/bethblog.com/wp-content/uploads/2013/02/Rage%20Tool%20Kit%20FAQ.pdf

To download the kit itself, be on the lookout for the RAGE Tool Kit in the Tools section of Steam.