Today I mentioned to my girlfriend that I was thinking of making a gaming diary to help keep track of games I would like to finish. She recommended this website:
https://backloggery.com/ that is specifically designed for people who want to do that!
Here's my page at the moment:
https://backloggery.com/Proxima . You can click on the "Unfinished", "Beaten" and "Completed" headings just under "Proxima's Status" to get my lists of unfinished, finished and 100% completed games
(Of course, I haven't yet gotten round to listing every game I've ever played -- mostly limiting it to the games I've played in the last couple of years, ever since
A Link to the Past started my streak of going back and playing so many of the classic console games I missed out on when I was younger.)
I am hoping to move as many as possible of the "Unfinished" and "Beaten" games to "Completed" over the next year!