A ddo file extension is related to the Tank3D video game. A ddo file stores game data.
DDO file extension - Tank3D game data
What is ddo file? How to open ddo files?
File type specification:
The ddo file extension was used in a very old game called Tank3D for one of its game data files.
Most likely some old format without support. No further information could be found.
This ddo file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.