Hi!

I got the vanilla mod from the MoO3 Guardian page http://www.moo3.at/mods/

I extracted it all to the directory but the game then just refuses to even start - am i missing something here?

thanks

RTFM that site

Summary
Danib in his signature states (Maintainer or New Author, not sure which one).
MediaFire - Danielboro. latest tropical 1.3.10 , full 1.3.10, update 1.3.7 to 1.3.10 ver2 newpart of 1.3.11 update

This is required as well
Master of Orion 3 Patcher - MoO3 DLL

Then RTFM the mods and sites linked + Guardian.

General Tip for Dead Sites
Best tip for dead sites, use Wayback Machine, gets the info and, though files are not downloaded if grouped outside pages, as most of these are HTML files, with a Folder attached, many presumed lost mods can be found buried in the web folders.