Might and Magic!

Then again, emulation also wreaks havoc on any backlog by adding games to it faster than anybody could humanly finish them.

Backlog keeper, congratulations on your recent discovery of (and, considering you finished them, affection for) the Phoenix Wright trilogy. These are games I can't help but finish within days of getting them, pulling long nights just to see how each case unfolds. Can't wait for Apollo Justice to hit about a month from now!

That's the best thing about emulators. The ability to play games one doesn't actually own. I'm currently going through and getting some ROMs of games that I haven't played in years, so I can go back and finally beat them, though on my own list I'm not going to add them until I've actually started then as a new game, which won't come until I can whittle down my list of unfinished games in the first place.
This site has seriously done wonders for my determination to beat games!

I'm including games that I've only ever played via emulator, since they are games I want to play through/have played through, too.

Also, I'm following my own criteria for Completed and Mastered. For Completed, I'm considering that as having a very, very good understanding of how the game works, and that I've beat it with 100%, or very near to that goal. For Mastered, I'm considering that as have a knowledge about a game above and beyond what people normally have, and can plan and playh through the game in a reletively short amount of time in comparison to a normal, more casual player.

Also, for Simcity games and Afterlife (or basically any open-ended building sim), I'm using the 4 categories as a baseline for skill in the game. Note that games in the Ceasar series don't count for this, as they have campaign modes, which need to be beaten before being able to say Beaten.