Files with tg1 file extension can be found as projects from On Target program.
TG1 file extension - On Target project
What is tg1 file? How to open tg1 files?
File type specification:
The tg1 file extension was reported to us for being used for project files in some older On Target program. No further information about the program or file type could be found, so it is either very rare or very old - and most likely obsolete.
This tg1 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.