Patching extra functionality into <gamemd.exe>

[CannisRabidus]

BTW, Cannis' question was about "which mix files the game searches for specific types of files in, can we change that order?"
See this page for exact info on how the game reads the files.

No, that's not my question. I'll go into more detail.

Although the mix files may well complicate things.

Put simplistically, right now if the game needs to call SOMEFILE.SHP, it looks in the program folder (\RA2\). Suppose it instead looked for SOMEFILE.SHP in \RA2\SUBDIR\, and if it didn't find the file there, it would fall back to looking in \RA2\.

The value of SUBDIR would be set by a command line parameter, like "-mod SUBDIR". This way SUBDIR can be anything you like...

For example, I could put all my mod files in a directory called 'cannisrules': \RA2\CANNISRULES\. When the game is run normally, the contents of that directory are ignored, of course. But if the game is run with the command line parameter "-mod cannisrules", then the game looks for files in that folder first, falling back to the default program directory for files that are not found.

This would mean that any number of mods could be installed at the same time, and the user could play any he wanted to by simply clicking on the appropriate edited shortcut. Plus, this would keep mod files out of the default directory where they really don't belong anyway...

(btw this is how Quake-based games operate)

This is like a holy grail for users, and therefore it should be a holy grail for modders too. Think of all the crappy mods that dump loads of loose files in your program folder. I have no idea if this can be done, but if it can be, then this is potentially the most important change of all IMO.