Volition and Deep Silver are serious about supporting modding in the future. As a result, developers like myself have finally been allowed to start talking about the engine and helping with the modding effort. I'm going to look around and respond to posts that I see with questions that I know the answers to, but before I did that I thought it would be a good idea to introduce myself. My name is Mike and I worked on RFG, SR3 and now SR4. I have done everything from tools to streaming, but most of my work has been in the file system and streaming. I am one of the people that deals with packfiles (vpp_pc), stream2 data files (str2_pc), and asset assembler files (asm_pc). I also know about a good deal of the other formats we use such as pegs, vbms, etc. I'm not on the art side of things, so I don't know much about the exporters and can't immediately answer questions like how to take your fancy tga and dump it into a cvbm/gvbm other than to tell you to run peg_assemble.exe, which you don't have access to...yet. I can help with questions like what bits in a header might mean and how to create asm files. I can also tell you that I'm working to try and make SR3 as mod friendly as I possibly can. Like you, I'm working on this stuff in my spare time, which admittedly is a little scarce right now for obvious reasons. Hopefully we will have more information for you soon. If you have a question, please don't direct message me or reply to this post because most questions will be useful for everyone and posting them in their own thread is the easiest way for them to be found in the future.