Today I cleaned again the whole system. After following the description in PDF I also used Windows Install Clean Up tool again. Further I searched for all files and folders on my main drive with the name of Tobii oder Tetserv oder Tetfw or whatever and deleted them, too. Than used CCleaner to delete all broken registry pathes. Than used the regscanner64 to search all traces of names with Tobii, Tetserver and Tetfw and deleted them, too.
Still after restart: Tobii is already installed, installation aborted.
There must be some reference which does not use any Tobii product reference in its name.
Further as the developer you should specifically know for sure what references get checked on the setup file. Which are they ?
Also some kind of way to force a full reinstall of the software would be helpful. Than I would not need to find any kind of traces and just freshly install everything by overwriting existing things.
Please help !