It's entirely possible that I haven't done it in anything since games started tracking it officially. I don't see anything at 100% in Steam (although a few things are close). I used to do it more often when I was younger and couldn't afford more games and had to make the ones I had last longer, so I'd do every optional/secret thing I could. If I could easily go back and check stuff on the SNES, for example (and all the other various things I've used from the 80s through today), I could come up with plenty. Too many games and not enough time these days, and not many of them make me want to keep playing after I'm done, so I don't end up doing ridiculous things out of boredom, only for fun.