This is a program to extract the contents of .t3d files belonging to the defunct 1997 Tank game called Tanarus

Tanarus was a fun game and this file format is dead simple. Having the original assets might spark interest in recreating the game for another engine? I don't know.. This could be part of a larger effort of reverse engineering the other file types that the engine uses "for fun".

I don't think that's a problem since the original engine is defunct anyway. Noone is creating any new t3d archives. If you do need to, there's always the Tanarus map editor which has ffcreate (which creates the t3d files)